Chubb (CHB) 10-K 28 Feb 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Feb. 14, 2014	Jun. 30, 2013
Document And Entity Information [Abstract]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Trading Symbol	'CB	'	'
Entity Registrant Name	'CHUBB CORP	'	'
Entity Central Index Key	'0000020171	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	245,597,652	'
Entity Public Float	'	'	$21,553,585,009

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues	'	'	'
Premiums Earned	$12,066	$11,838	$11,644
Investment Income	1,465	1,556	1,644
Other Revenues	14	8	9
Realized Investment Gains (Losses), Net	'	'	'
Total Other-Than-Temporary Impairment Losses on Investments	-11	-40	-22
Other-Than-Temporary Impairment Losses on Investments Recognized in Other Comprehensive Income	'	-5	-1
Other Realized Investment Gains, Net	413	238	311
Total Realized Investment Gains, Net	402	193	288
TOTAL REVENUES	13,947	13,595	13,585
Losses and Expenses	'	'	'
Losses and Loss Expenses	6,520	7,507	7,407
Amortization of Deferred Policy Acquisition Costs	2,454	2,411	2,330
Other Insurance Operating Costs and Expenses	1,411	1,362	1,312
Investment Expenses	49	38	39
Other Expenses	22	11	11
Corporate Expenses	254	270	287
TOTAL LOSSES AND EXPENSES	10,710	11,599	11,386
INCOME BEFORE FEDERAL AND FOREIGN INCOME TAX	3,237	1,996	2,199
Federal and Foreign Income Tax	892	451	521
NET INCOME	$2,345	$1,545	$1,678
Net Income Per Share	'	'	'
Basic	$9.08	$5.73	$5.80
Diluted	$9.04	$5.69	$5.76

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]	'	'	'
Net Income	$2,345	$1,545	$1,678
Other Comprehensive Income (Loss), Net of Tax	'	'	'
Change in Unrealized Appreciation of Investments	-788	275	615
Change in Unrealized Other-Than-Temporary Impairment Losses on Investments	'	2	1
Change in Postretirement Benefit Costs Not Yet Recognized in Net Income	464	-30	-215
Foreign Currency Translation Gains (Losses)	-72	-11	4
Total Other Comprehensive Income (Loss) Net of Tax	-396	236	405
COMPREHENSIVE INCOME	$1,949	$1,781	$2,083

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Assets	'	'
Short Term Investments	$2,114	$2,528
Fixed Maturities (cost $35,959 and $35,398)	37,091	38,076
Equity Securities (cost $1,057 and $1,244)	1,810	1,663
Other Invested Assets	1,598	1,954
TOTAL INVESTED ASSETS	42,613	44,221
Cash	52	50
Accrued Investment Income	418	424
Premiums Receivable	2,284	2,185
Reinsurance Recoverable on Unpaid Losses and Loss Expenses	1,802	1,941
Prepaid Reinsurance Premiums	290	337
Deferred Policy Acquisition Costs	1,255	1,206
Deferred Income Tax	47	'
Goodwill	467	467
Other Assets	1,205	1,353
TOTAL ASSETS	50,433	52,184
Liabilities	'	'
Unpaid Losses and Loss Expenses	23,146	23,963
Unearned Premiums	6,423	6,361
Long Term Debt	3,300	3,575
Dividend Payable to Shareholders	110	108
Deferred Income Tax	'	162
Accrued Expenses and Other Liabilities	1,357	2,188
TOTAL LIABILITIES	34,336	36,357
Commitments and Contingent Liabilities (Note 5 and 12)	'	'
Shareholders' Equity	'	'
Preferred Stock - Authorized 8,000,000 Shares; $1 Par Value; Issued - None	'	'
Common Stock - Authorized 1,200,000,000 Shares; $1 Par Value; Issued 371,980,460 Shares	372	372
Paid-In Surplus	171	178
Retained Earnings	21,902	20,009
Accumulated Other Comprehensive Income	1,035	1,431
Treasury Stock, at Cost - 123,673,969 and 110,217,445 Shares	-7,383	-6,163
TOTAL SHAREHOLDERS' EQUITY	16,097	15,827
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$50,433	$52,184

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, except Share data, unless otherwise specified
Statement Of Financial Position [Abstract]	'	'
Fixed Maturities, cost	$35,959	$35,398
Equity Securities, cost	$1,057	$1,244
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Preferred Stock, Par Value	$1	$1
Preferred Stock, Shares Issued	'	'
Common Stock, Shares Authorized	1,200,000,000	1,200,000,000
Common Stock, Par Value	$1	$1
Common Stock, Shares Issued	371,980,460	371,980,460
Treasury Stock, Shares	123,673,969	110,217,445

Consolidated_Statements_of_Sha

Consolidated Statements of Shareholders' Equity (USD $)	Total	Preferred Stock [Member]	Common Stock [Member]	Paid-In-Surplus [Member]	Retained Earnings [Member]	Unrealized Appreciation of Investments Including Unrealized Other-Than-Temporary Impairment Losses [Member]	Postretirement Benefit Costs Not Yet Recognized in Net Income [Member]	Foreign Currency Translation Gains [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock, at Cost [Member]
In Millions
Balance, Beginning of Year at Dec. 31, 2010	'	'	$372	$208	$17,670	$1,120	($472)	$142	'	($3,783)
Net Income	1,678	'	'	'	1,678	'	'	'	'	'
Repurchase of Shares	'	'	'	'	'	'	'	'	'	-1,718
Changes Related to Stock-Based Employee Compensation (includes tax benefit of $28, $27 and $24)	'	'	'	-18	'	'	'	'	'	'
Change During Year, Net of Tax	405	'	'	'	'	616	-215	4	'	'
Dividends Declared (per share $1.76, $1.64 and $1.56)	'	'	'	'	-445	'	'	'	'	'
Shares Issued Under Stock-Based Employee Compensation Plans	'	'	'	'	'	'	'	'	'	142
Balance, End of Year at Dec. 31, 2011	15,301	'	372	190	18,903	1,736	-687	146	1,195	-5,359
Net Income	1,545	'	'	'	1,545	'	'	'	'	'
Repurchase of Shares	'	'	'	'	'	'	'	'	'	-935
Changes Related to Stock-Based Employee Compensation (includes tax benefit of $28, $27 and $24)	'	'	'	-12	'	'	'	'	'	'
Change During Year, Net of Tax	236	'	'	'	'	277	-30	-11	'	'
Dividends Declared (per share $1.76, $1.64 and $1.56)	'	'	'	'	-439	'	'	'	'	'
Shares Issued Under Stock-Based Employee Compensation Plans	'	'	'	'	'	'	'	'	'	131
Balance, End of Year at Dec. 31, 2012	15,827	'	372	178	20,009	2,013	-717	135	1,431	-6,163
Net Income	2,345	'	'	'	2,345	'	'	'	'	'
Repurchase of Shares	'	'	'	'	'	'	'	'	'	-1,300
Changes Related to Stock-Based Employee Compensation (includes tax benefit of $28, $27 and $24)	'	'	'	-7	'	'	'	'	'	'
Change During Year, Net of Tax	-396	'	'	'	'	-788	464	-72	'	'
Dividends Declared (per share $1.76, $1.64 and $1.56)	'	'	'	'	-452	'	'	'	'	'
Shares Issued Under Stock-Based Employee Compensation Plans	'	'	'	'	'	'	'	'	'	80
Balance, End of Year at Dec. 31, 2013	$16,097	'	$372	$171	$21,902	$1,225	($253)	$63	$1,035	($7,383)

Consolidated_Statements_of_Sha1

Consolidated Statements of Shareholders' Equity (Parenthetical) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Paid-In-Surplus [Member]	'	'	'
Tax Benefit, Stock-Based Employee Compensation	$28	$27	$24
Retained Earnings [Member]	'	'	'
Dividends Declared Per Share	$1.76	$1.64	$1.56

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities	'	'	'
Net Income	$2,345	$1,545	$1,678
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities	'	'	'
Increase (Decrease) in Unpaid Losses and Loss Expenses, Net	-582	691	361
Increase in Unearned Premiums, Net	158	32	114
Increase in Premiums Receivable	-99	-24	-63
Change in Income Tax Payable or Recoverable	93	-53	-102
Amortization of Premiums and Discounts on Fixed Maturities	183	163	147
Depreciation	55	54	58
Realized Investment Gains, Net	-402	-193	-288
Other, Net	-20	84	-27
NET CASH PROVIDED BY OPERATING ACTIVITIES	1,731	2,299	1,878
Cash Flows from Investing Activities	'	'	'
Proceeds from Fixed Maturities - Sales	2,449	2,271	1,730
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions	4,909	4,290	3,540
Proceeds from Sales of Equity Securities	545	160	167
Purchases of Fixed Maturities	-8,275	-7,247	-5,014
Purchases of Equity Securities	-113	-112	-95
Investments in Other Invested Assets, Net	498	293	285
Decrease (Increase) in Short Term Investments, Net	383	-629	11
Change in Receivable or Payable from Security Transactions not Settled, Net	-86	45	8
Purchases of Property and Equipment, Net	-52	-43	-52
Other, Net	-6	'	'
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	252	-972	580
Cash Flows from Financing Activities	'	'	'
Repayment of Long Term Debt	-275	'	-400
Increase (Decrease) in Funds Held under Deposit Contracts	-6	-12	7
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	38	74	80
Repurchase of Shares	-1,288	-959	-1,707
Dividends Paid to Shareholders	-450	-438	-450
NET CASH USED IN FINANCING ACTIVITIES	-1,981	-1,335	-2,470
Net Increase (Decrease) in Cash	2	-8	-12
Cash at Beginning of Year	50	58	70
CASH AT END OF YEAR	$52	$50	$58

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	(1)  Summary of Significant Accounting Policies
	(a)	Basis of Presentation
	The Chubb Corporation (Chubb) is a holding company with subsidiaries principally engaged in the property and casualty insurance business. The property and casualty insurance subsidiaries (the P&C Group) underwrite most lines of property and casualty insurance in the United States, Canada, Europe, Australia and parts of Latin America and Asia. The geographic distribution of property and casualty business in the United States is broad with a particularly strong market presence in the Northeast.
	The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include the accounts of Chubb and its subsidiaries (collectively, the Corporation). Significant intercompany transactions have been eliminated in consolidation. The results of our operations in Australia, Brazil and other smaller foreign locations are recorded on a three month lag in our consolidated financial statements. Specific events having significant financial impact that occur during the lag period are included in the current period results.
	The consolidated financial statements include amounts based on informed estimates and judgments of management for transactions that are not yet complete. Such estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Certain amounts in the consolidated financial statements for prior years have been reclassified to conform with the 2013 presentation.
	(b)	Invested Assets
	Short term investments, which have an original maturity of one year or less, are carried at amortized cost, which approximates fair value.
	Fixed maturities, which include taxable and tax exempt bonds, are classified as available-for-sale and carried at fair value as of the balance sheet date. Taxable bonds include U.S. government and government agency and authority obligations, including taxable bonds issued by states, municipalities and political subdivisions within the United States, and foreign government and government agency obligations, corporate bonds and mortgage-backed securities. Corporate bonds include redeemable preferred stocks. Tax exempt bonds consist of bonds issued by states, municipalities and political subdivisions within the United States. Fixed maturities are purchased to support the investment strategies of the Corporation. These strategies are developed based on many factors including rate of return, maturity, credit risk, tax considerations and regulatory requirements. Fixed maturities may be sold prior to maturity to support the investment strategies of the Corporation.
	Premiums and discounts arising from the purchase of fixed maturities are amortized using the interest method over the estimated remaining term of the securities. For mortgage-backed securities, prepayment assumptions are reviewed periodically and revised as necessary.
	Equity securities, which include common stocks and non-redeemable preferred stocks, are carried at fair value as of the balance sheet date.
	Unrealized appreciation or depreciation, including unrealized other-than-temporary impairment losses, of fixed maturities and equity securities carried at fair value is excluded from net income and is included, net of applicable deferred income tax, in other comprehensive income.
	Other invested assets primarily include private equity limited partnerships which are carried at the Corporation’s equity in the net assets of the partnerships based on valuations provided by the manager of each partnership. As a result of the timing of the receipt of valuation data from the investment managers, these investments are generally reported on a three month lag. Changes in the Corporation’s equity in the net assets of the partnerships are included in net income as realized investment gains or losses. Other invested assets also include warrants, which are carried at fair value as of the balance sheet date. Changes in the fair value of warrants are included in net income as realized investment gains or losses.
	Realized gains and losses on the sale of investments are determined on the basis of the cost of the specific investments sold and are included in net income.
	When the fair value of an investment is lower than its cost, an assessment is made to determine whether the decline is temporary or other than temporary. The assessment of other-than-temporary impairment of fixed maturities and equity securities is based on both quantitative criteria and qualitative information. A number of factors are considered including, but not limited to, the length of time and the extent to which the fair value has been less than the cost, the financial condition and near term prospects of the issuer, whether the issuer is current on contractually obligated interest and principal payments, general market conditions and industry or sector specific factors.
	In determining whether fixed maturities are other than temporarily impaired, the Corporation is required to recognize an other-than-temporary impairment loss when it concludes it has the intent to sell or it is more likely than not it will be required to sell an impaired fixed maturity before the security recovers to its amortized cost value or it is likely it will not recover the entire amortized cost value of an impaired security. If the Corporation has the intent to sell or it is more likely than not that the Corporation will be required to sell an impaired fixed maturity before the security recovers to its amortized cost value, the security is written down to fair value and the entire amount of the writedown is included in net income as a realized investment loss. For all other impaired fixed maturities, when the impairment is determined to be other than temporary, the impairment loss is separated into the amount representing the credit loss and the amount representing the loss related to all other factors. The amount of the impairment loss that represents the credit loss is included in net income as a realized investment loss and the amount of the impairment loss that relates to all other factors is included in other comprehensive income.
	For fixed maturities, the split between the amount of other-than-temporary impairment losses that represents credit losses and the amount that relates to all other factors is principally based on assumptions regarding the amount and timing of projected cash flows. For fixed maturities other than mortgage-backed securities, cash flow estimates are based on assumptions regarding the probability of default and estimates regarding the timing and amount of recoveries associated with a default. For mortgage-backed securities, cash flow estimates are based on assumptions regarding future prepayment rates, default rates, loss severity and timing of recoveries. The Corporation has developed the estimates of projected cash flows using information based on historical market data, industry analyst reports and forecasts and other data relevant to the collectibility of a security.
	In determining whether equity securities are other than temporarily impaired, the Corporation considers its intent and ability to hold a security for a period of time sufficient to allow for the recovery of cost. If the decline in the fair value of an equity security is deemed to be other than temporary, the security is written down to fair value and the amount of the writedown is included in net income as a realized investment loss.
	(c)	Premium Revenues and Related Expenses
	Insurance premiums are earned on a monthly pro rata basis over the terms of the policies and include estimates of audit premiums and premiums on retrospectively rated policies. Assumed reinsurance premiums are earned over the terms of the reinsurance contracts. Unearned premiums represent the portion of direct and assumed premiums written applicable to the unexpired terms of the insurance policies and reinsurance contracts in force.
	Ceded reinsurance premiums are reflected in operating results over the terms of the reinsurance contracts. Prepaid reinsurance premiums represent the portion of premiums ceded to reinsurers applicable to the unexpired terms of the reinsurance contracts in force.
	Reinsurance reinstatement premiums are recognized in the same period as the loss event that gave rise to the reinstatement premiums.
	Acquisition costs that are directly related to the successful acquisition of new or renewal insurance contracts are deferred and amortized over the period in which the related premiums are earned. Such costs include commissions, premium taxes and certain other underwriting and policy issuance costs. Commissions received related to reinsurance premiums ceded are considered in determining net acquisition costs eligible for deferral. Deferred policy acquisition costs are reviewed to determine whether they are recoverable from future income. If such costs are deemed to be unrecoverable, they are expensed. Anticipated investment income is considered in the determination of the recoverability of deferred policy acquisition costs.
	(d)	Unpaid Losses and Loss Expenses
	Unpaid losses and loss expenses (also referred to as loss reserves) include the accumulation of individual case estimates for claims that have been reported and estimates of claims that have been incurred but not reported as well as estimates of the expenses associated with processing and settling all reported and unreported claims, less estimates of anticipated salvage and subrogation recoveries. Estimates are based upon past loss experience modified for current trends as well as prevailing economic, legal and social conditions. Loss reserves are not discounted to present value.
	Loss reserves are regularly reviewed using a variety of actuarial techniques. Reserve estimates are updated as historical loss experience develops, additional claims are reported and/or settled and new information becomes available. Any changes in estimates are reflected in operating results in the period in which the estimates are changed.
	Reinsurance recoverable on unpaid losses and loss expenses represents an estimate of the portion of gross loss reserves that will be recovered from reinsurers. Amounts recoverable from reinsurers are estimated using assumptions that are consistent with those used in estimating the gross losses associated with the reinsured policies. A provision for estimated uncollectible reinsurance is recorded based on periodic evaluations of balances due from reinsurers, the financial condition of the reinsurers, coverage disputes and other relevant factors.
	(e)	Financial Products
	Derivatives are carried at fair value as of the balance sheet date. Changes in fair value are recognized in net income in the period of the change and are included in other revenues.
	Assets and liabilities related to the derivatives are included in other assets and other liabilities.
	(f)	Goodwill
	Goodwill represents the excess of the cost of an acquired entity over the fair value of net assets acquired. Goodwill is tested for impairment at least annually.
	(g)	Property and Equipment
	Property and equipment used in operations, including certain costs incurred to develop or obtain computer software for internal use, are capitalized and carried at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. Property and equipment are included in other assets.
	(h)	Real Estate
	Real estate properties are carried at cost less accumulated depreciation and any writedowns for impairment. Real estate properties are reviewed for impairment whenever events or circumstances indicate that the carrying value of such properties may not be recoverable. Measurement of such impairment is based on the fair value of the property. Real estate properties are included in other assets.
	(i)	Income Taxes
	Deferred income tax assets and liabilities are recognized for the expected future tax effects attributable to temporary differences between the financial reporting and tax bases of assets and liabilities, based on enacted tax rates and other provisions of tax law. The effect on deferred tax assets and liabilities of a change in tax laws or rates is recognized in net income in the period in which such change is enacted. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax assets will not be realized.
	The Corporation does not consider the earnings of its foreign subsidiaries to be permanently reinvested. Accordingly, provision has been made for the expected U.S. federal income tax liabilities applicable to undistributed earnings of foreign subsidiaries.
	(j)	Stock-Based Employee Compensation
	The fair value method of accounting is used for stock-based employee compensation plans. Under the fair value method, compensation cost is measured based on the fair value of the award at the grant date and recognized over the requisite service period.
	(k)	Foreign Exchange
	Assets and liabilities relating to foreign operations are translated into U.S. dollars using current exchange rates as of the balance sheet date. Revenues and expenses are translated into U.S. dollars using the average exchange rates during the year.
	The functional currency of foreign operations is generally the currency of the local operating environment since business is primarily transacted in such local currency. Translation gains and losses, net of applicable income tax, are excluded from net income and are credited or charged directly to other comprehensive income.
	(l)	Cash Flow Information
	In the statement of cash flows, short term investments are not considered to be cash equivalents. The effect of changes in foreign exchange rates on cash balances was insignificant.
	In 2013, the Corporation exchanged its holdings of common stock and warrants of Alterra Capital Holdings Limited, with a cost basis of $177 million and a carrying value of $63 million, respectively, for common stock of Markel Corporation, valued at $226 million, and cash of $98 million, as a result of a business combination. The noncash portions of the transaction have been excluded from the statement of cash flows.

Invested_Assets_and_Related_In

Invested Assets and Related Income	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Invested Assets and Related Income	'
	(2)  Invested Assets and Related Income
	(a)  The amortized cost and fair value of fixed maturities and equity securities were as follows:
		December 31, 2013
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Appreciation			Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	17,808		$	802		$	189		$	18,421
	Taxable
	U.S. government and government agency and		784			27			9			802
	authority obligations
	Corporate bonds		9,032			370			88			9,314
	Foreign government and government agency obligations		6,719			206			35			6,890
	Residential mortgage-backed securities		277			23			1			299
	Commercial mortgage-backed securities		1,339			29			3			1,365
			18,151			655			136			18,670
	Total fixed maturities	$	35,959		$	1,457		$	325		$	37,091
	Equity securities	$	1,057		$	756		$	3		$	1,810
		December 31, 2012
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Appreciation			Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	18,410		$	1,522		$	19		$	19,913
	Taxable
	U.S. government and government agency and authority obligations		973			66			—			1,039
	Corporate bonds		7,331			609			3			7,937
	Foreign government and government agency obligations		6,614			395			1			7,008
	Residential mortgage-backed securities		421			36			2			455
	Commercial mortgage-backed securities		1,649			76			1			1,724
			16,988			1,182			7			18,163
	Total fixed maturities	$	35,398		$	2,704		$	26		$	38,076
	Equity securities	$	1,244		$	453		$	34		$	1,663
	The following table summarizes the fair value of the tax exempt fixed maturities at December 31, 2013 and 2012:
		2013			2012
		(in millions)
	Special revenue bonds	$	11,717		$	12,233
	State general obligation bonds		2,292			2,246
	Municipal and political subdivision general obligation bonds		2,220			2,505
	Pre-refunded bonds		2,192			2,929
		$	18,421		$	19,913
	Special revenue bonds are supported by income streams generated in a broad range of sectors, primarily highways, hospitals, water and sewer utilities, electric utilities, airports, universities and housing, as well as specifically pledged tax revenues. The special revenue bond holdings are well-diversified and spread relatively evenly over these sectors. An irrevocable trust containing U.S. government or government agency obligations has been established to fund the remaining principal and interest payments of the pre-refunded bonds.
	The following table summarizes the fair value and amortized cost of the tax exempt fixed maturities other than pre-refunded bonds held at December 31, 2013 and 2012, for the five states having the largest concentration of issuers within the tax exempt fixed maturity portfolio. The remainder of tax exempt fixed maturities were issued by a broad range of other states and municipalities and political subdivisions within those states. In the following table, “state” identifies the issuer or the location of the issuing municipality or political subdivision within a state.
		December 31, 2013
		Fair Value
	State	Special			Municipal			State			Total		Amortized
		Revenue			and  Political			General					Cost
		Bonds			Subdivision			Obligations
					General
					Obligations
		(in millions)
	Texas	$	930		$	830		$	230		$	1,990	$	1,904
	New York		1,611			197			31			1,839		1,809
	California		859			82			198			1,139		1,093
	Illinois		577			483			56			1,116		1,094
	Florida		757			38			108			903		877
		December 31, 2012
		Fair Value
	State	Special			Municipal			State			Total		Amortized
		Revenue			and Political			General					Cost
		Bonds			Subdivision			Obligations
		General
		Obligations
	(in millions)
Texas	$	1,041		$	1,053		$	267		$	2,361	$	2,171
New York		1,401			169			33			1,603		1,487
Illinois		683			518			59			1,260		1,161
California		888			107			194			1,189		1,089
Florida		771			27			114			912		844
At December 31, 2013 and 2012, foreign government and government agency fixed maturities consisted of high quality fixed maturities primarily issued by national governments and, to a lesser extent, government agencies, regional governments and supranational organizations.
The following table summarizes the fair value and amortized cost of the foreign government and government agency fixed maturities held at December 31, 2013 and 2012, for the five countries having the largest concentration of issuers within the foreign government and government agency fixed maturity portfolio. In the following table, “country” identifies the issuer or the location of the issuing government agency or regional government within a country.
	2013						2012
Country	Fair			Amortized			Fair			Amortized
	Value			Cost			Value			Cost
	(in millions)
Canada	$	1,993		$	1,953		$	2,157		$	2,060
Germany		1,241			1,211			1,127			1,070
United Kingdom		1,026			1,004			1,024			939
Australia		739			700			742			663
Brazil		270			270			310			310
At December 31, 2013 and 2012, the foreign government and government agency fixed maturities also included $547 million and $517 million, respectively, of fixed maturities issued by supranational organizations.
The fair value and amortized cost of fixed maturities at December 31, 2013 by contractual maturity were as follows:
	Fair			Amortized
	Value			Cost
	(in millions)
Due in one year or less	$	2,241		$	2,212
Due after one year through five years		13,769			13,202
Due after five years through ten years		11,743			11,294
Due after ten years		7,674			7,635
		35,427			34,343
Residential mortgage-backed securities		299			277
Commercial mortgage-backed securities		1,365			1,339
	$	37,091		$	35,959
Actual maturities could differ from contractual maturities because borrowers may have the right to call or prepay obligations.
The Corporation’s equity securities comprise a diversified portfolio of primarily U.S. publicly-traded common stocks.
The Corporation is involved in the normal course of business with variable interest entities (VIEs) primarily as a passive investor in residential mortgage-backed securities, commercial mortgage-backed securities and private equity limited partnerships issued by third party VIEs. The Corporation is not the primary beneficiary of these VIEs. The Corporation’s maximum exposure to loss with respect to these investments is limited to the investment carrying values included in the Corporation’s consolidated balance sheet and any unfunded partnership commitments.
(b)  The components of unrealized appreciation or depreciation, including unrealized other-than-temporary impairment losses, of investments carried at fair value were as follows:
	December 31
	2013			2012
	(in millions)
Fixed maturities
Gross unrealized appreciation	$	1,457		$	2,704
Gross unrealized depreciation		325			26
		1,132			2,678
Equity securities
Gross unrealized appreciation		756			453
Gross unrealized depreciation		3			34
		753			419
		1,885			3,097
Deferred income tax liability		660			1,084
	$	1,225		$	2,013
The following table summarizes, for all investment securities in an unrealized loss position at December 31, 2013, the aggregate fair value and gross unrealized depreciation, including unrealized other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position.
	Less Than 12 Months						12 Months or More					Total
	Fair			Gross			Fair			Gross		Fair		Gross
	Value			Unrealized			Value			Unrealized		Value		Unrealized
				Depreciation						Depreciation				Depreciation
	(in millions)
Fixed maturities
Tax exempt	$	3,417		$	144		$	307		$	45	$	3,724	$	189
Taxable
U.S. government and government agency		213			6			35			3		248		9
and authority obligations
Corporate bonds		2,526			76			222			12		2,748		88
Foreign government and government		1,735			32			75			3		1,810		35
agency obligations
Residential mortgage-backed securities		4			—			14			1		18		1
Commercial mortgage-backed securities		153			1			39			2		192		3
		4,631			115			385			21		5,016		136
Total fixed maturities		8,048			259			692			66		8,740		325
Equity securities		41			3			—			—		41		3
	$	8,089		$	262		$	692		$	66	$	8,781	$	328
At December 31, 2013, approximately 1,160 individual fixed maturities and 10 individual equity securities were in an unrealized loss position. The Corporation does not have the intent to sell and it is not more likely than not that the Corporation will be required to sell these fixed maturities before the securities recover to their amortized cost value. In addition, the Corporation believes that none of the declines in the fair values of these fixed maturities relate to credit losses. The Corporation has the intent and ability to hold the equity securities in an unrealized loss position for a period of time sufficient to allow for the recovery of cost. The Corporation believes that none of the declines in the fair value of these fixed maturities and equity securities were other than temporary at December 31, 2013.
The following table summarizes, for all investment securities in an unrealized loss position at December 31, 2012, the aggregate fair value and gross unrealized depreciation, including unrealized other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position.
	Less Than 12 Months						12 Months or More					Total
	Fair			Gross			Fair			Gross		Fair		Gross
	Value			Unrealized			Value			Unrealized		Value		Unrealized
				Depreciation						Depreciation				Depreciation
	(in millions)
Fixed maturities
Tax exempt	$	344		$	6		$	104		$	13	$	448	$	19
Taxable
U.S. government and government agency and authority obligations		28			—			20			—		48		—
Corporate bonds		289			2			14			1		303		3
Foreign government and government agency obligations		429			1			13			—		442		1
Residential mortgage-backed securities		1			—			19			2		20		2
Commercial mortgage-backed securities		105			1			3			—		108		1
		852			4			69			3		921		7
Total fixed maturities		1,196			10			173			16		1,369		26
Equity securities		182			21			63			13		245		34
	$	1,378		$	31		$	236		$	29	$	1,614	$	60
The change in unrealized appreciation or depreciation of investments carried at fair value, including the change in unrealized other-than-temporary impairment losses, was as follows:
	Years Ended December 31
	2013			2012			2011
	(in millions)
Change in unrealized appreciation of fixed maturities	$	(1,546	)	$	256		$	964
Change in unrealized appreciation of equity securities		334			171			(17	)
		(1,212	)		427			947
Deferred income tax (credit)		(424	)		150			331
	$	(788	)	$	277		$	616
(c)  The sources of net investment income were as follows:
	Years Ended December 31
	2013			2012			2011
	(in millions)
Fixed maturities	$	1,380		$	1,465		$	1,549
Equity securities		38			40			34
Short term investments		16			18			16
Other		31			33			45
Gross investment income		1,465			1,556			1,644
Investment expenses		49			38			39
	$	1,416		$	1,518		$	1,605
(d)  Realized investment gains and losses were as follows:
	Years Ended December 31
	2013			2012			2011
	(in millions)
Fixed maturities
Gross realized gains	$	62		$	124		$	70
Gross realized losses		(42	)		(20	)		(39	)
Other-than-temporary impairment losses		(2	)		(5	)		(1	)
		18			99			30
Equity securities
Gross realized gains		204			68			74
Gross realized losses		(1	)		—			(1	)
Other-than-temporary impairment losses		(9	)		(40	)		(22	)
		194			28			51
Other invested assets		190			66			207
	$	402		$	193		$	288
(e)  As of December 31, 2013 and 2012, fixed maturities still held by the Corporation for which a portion of their other-than-temporary impairment losses were recognized in other comprehensive income had cumulative credit-related losses of $20 million and $22 million, respectively, recognized in net income.

Deferred_Policy_Acquisition_Co

Deferred Policy Acquisition Costs	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Deferred Policy Acquisition Costs	'
	(3)  Deferred Policy Acquisition Costs
	Policy acquisition costs deferred and the related amortization reflected in operating results were as follows:
		Years Ended December 31
		2013			2012			2011
					(in millions)
	Balance, beginning of year	$	1,206		$	1,210		$	1,142
	Costs deferred during year
	Commissions and brokerage		1,979			1,919			1,910
	Premium taxes and assessments		263			247			235
	Underwriting and policy issuance costs		271			248			248
			2,513			2,414			2,393
	Foreign currency translation effect		(10	)		(7	)		5
	Amortization during year		(2,454	)		(2,411	)		(2,330	)
	Balance, end of year	$	1,255		$	1,206		$	1,210

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Property and Equipment	'
	(4)  Property and Equipment
	Property and equipment included in other assets were as follows:
		December 31
		2013		2012
		(in millions)
	Cost	$	501	$	517
	Accumulated depreciation		243		248
		$	258	$	269
	Depreciation expense related to property and equipment was $55 million, $54 million and $58 million for 2013, 2012, and 2011, respectively.

Unpaid_Losses_and_Loss_Expense

Unpaid Losses and Loss Expenses	12 Months Ended
	Dec. 31, 2013
Insurance [Abstract]	'
Unpaid Losses and Loss Expenses	'
	(5)  Unpaid Losses and Loss Expenses
	(a)  The process of establishing loss reserves is complex and imprecise as it must take into consideration many variables that are subject to the outcome of future events. As a result, informed subjective estimates and judgments as to the P&C Group’s ultimate exposure to losses are an integral component of the loss reserving process. The loss reserve estimation process relies on the basic assumption that past experience, adjusted for the effects of current developments and likely trends, is an appropriate basis for predicting future outcomes.
	Most of the P&C Group’s loss reserves relate to long tail liability classes of business. For many liability claims, significant periods of time, ranging up to several years or more, may elapse between the occurrence of the loss, the reporting of the loss and the settlement of the claim. The longer the time span between the incidence of a loss and the settlement of the claim, the more the ultimate settlement amount can vary.
	There are numerous factors that contribute to the inherent uncertainty in the process of establishing loss reserves. Among these factors are changes in the inflation rate for goods and services related to covered damages such as medical care and home repair costs; changes in the judicial interpretation of policy provisions relating to the determination of coverage; changes in the general attitude of juries in the determination of liability and damages; legislative actions; changes in the medical condition of claimants; changes in the estimates of the number and/or severity of claims that have been incurred but not reported as of the date of the financial statements; and changes in the P&C Group’s book of business, underwriting standards and/or claim handling procedures.
	In addition, the uncertain effects of emerging or potential claims and coverage issues that arise as legal, judicial and social conditions change must be taken into consideration. These issues have had, and may continue to have, a negative effect on loss reserves by either extending coverage beyond the original underwriting intent or by increasing the number or size of claims. As a result of such issues, the uncertainties inherent in estimating ultimate claim costs on the basis of past experience have grown, further complicating the already complex loss reserving process.
	Management believes that the aggregate loss reserves of the P&C Group at December 31, 2013 were adequate to cover claims for losses that had occurred as of that date, including both those known and those yet to be reported. In establishing such reserves, management considers facts currently known and the present state of the law and coverage litigation. However, given the significant uncertainties inherent in the loss reserving process, it is possible that management’s estimate of the ultimate liability for losses that had occurred as of December 31, 2013 may change, which could have a material effect on the Corporation’s results of operations and financial condition.
	(b)  A reconciliation of the beginning and ending liability for unpaid losses and loss expenses, net of reinsurance recoverable, and a reconciliation of the net liability to the corresponding liability on a gross basis is as follows:
		2013			2012			2011
		(in millions)
	Gross liability, beginning of year	$	23,963		$	23,068		$	22,718
	Reinsurance recoverable, beginning of year		1,941			1,739			1,817
	Net liability, beginning of year		22,022			21,329			20,901
	Net incurred losses and loss expenses related to
	Current year		7,232			8,121			8,174
	Prior years		(712	)		(614	)		(767	)
			6,520			7,507			7,407
	Net payments for losses and loss expenses related to
	Current year		2,150			2,323			2,746
	Prior years		4,952			4,493			4,300
			7,102			6,816			7,046
	Foreign currency translation effect		(96	)		2			67
	Net liability, end of year		21,344			22,022			21,329
	Reinsurance recoverable, end of year		1,802			1,941			1,739
	Gross liability, end of year	$	23,146		$	23,963		$	23,068
	Changes in loss reserve estimates are unavoidable because such estimates are subject to the outcome of future events. Loss trends vary and time is required for changes in trends to be recognized and confirmed. During 2013, the P&C Group experienced overall favorable development of $712 million on net unpaid losses and loss expenses established as of the previous year end. This compares with favorable prior year development of $614 million in 2012 and $767 million in 2011. Such favorable development was reflected in operating results in these respective years.
	The net favorable development of $712 million in 2013 was due to various factors. Favorable development of about $265 million in the aggregate, including $30 million related to catastrophes, was experienced in the personal and commercial property classes, mostly related to the 2012 and 2011 accident years. The severity and frequency of late developing property claims that emerged during 2013 were lower than expected, including those related to catastrophes, and the development of existing case reserves was more favorable than expected. Overall favorable development of about $260 million was experienced in the professional liability classes other than fidelity. This favorable development was driven by the directors and officers liability and fiduciary liability classes, partially offset by adverse development in the errors and omissions liability and employment practices liability classes. The reported loss activity was less than expected, with aggregate favorable emergence from accident years 2010 and prior. Favorable development of about $160 million in the aggregate was experienced in the personal and commercial liability classes. The most significant favorable development occurred in the excess liability classes, particularly in accident years 2010 and prior. There was some offsetting adverse development in other liability classes, most notably due to $106 million of incurred losses related to asbestos and toxic waste claims in older accident years. Overall, prior period liability claims were lower than expected, particularly the severity of such claims, and the effects of underwriting changes that affected these years have been more positive than expected. Unfavorable development of about $50 million was experienced in the fidelity class due to higher than expected reported loss emergence, related mostly to accident years subsequent to 2007. Favorable development of about $35 million was experienced in the personal automobile business due primarily to more favorable case reserve development and lower severity of prior period claims than expected. Favorable development of about $30 million was experienced in the surety business due to lower than expected loss emergence in recent accident years.
	The net favorable development of $614 million in 2012 was due to various factors. Favorable development of about $250 million in the aggregate was experienced in the personal and commercial liability classes. The most significant favorable development occurred in accident years 2006 to 2009, which more than offset adverse development in accident years 2002 and prior, which included $83 million of incurred losses related to asbestos and toxic waste claims. The overall frequency and severity of prior period liability claims were lower than expected and the effects of underwriting changes that affected these years have been more positive than expected, especially in the commercial excess liability class. Overall favorable development of about $200 million was experienced in the professional liability classes other than fidelity. This favorable development was driven by the directors and officers liability and fiduciary liability classes, partially offset by adverse development experienced in the errors and omissions liability and employment practices liability classes. The reported loss activity was less than expected, with aggregate favorable emergence from accident years 2008 and prior partly offset by some adverse emergence in the more recent accident years. Favorable development of about $125 million in the aggregate was experienced in the personal and commercial property classes, mostly related to the 2007 through 2011 accident years. The severity and frequency of late developing property claims that emerged during 2012 were lower than expected, including those related to catastrophes, and the development of existing case reserves was more favorable than expected. Unfavorable development of about $60 million was experienced in the fidelity class due to higher than expected reported loss emergence, related mostly to accident years 2008 through 2010. Favorable development of about $45 million was experienced in the runoff of our reinsurance assumed business due primarily to better than expected reported loss activity from cedants. Favorable development of about $40 million was experienced in the personal automobile business due primarily to lower than expected frequency of prior period claims. Favorable development of about $25 million was experienced in the surety business due to lower than expected loss emergence in recent accident years.
	The net favorable development of $767 million in 2011 was due to various factors. Favorable development of about $355 million in the aggregate was experienced in the personal and commercial liability classes. Favorable development in the more recent accident years, particularly in accident years 2004 to 2009, more than offset adverse development in accident years 2001 and prior, which included $72 million of incurred losses related to asbestos and toxic waste claims. The overall frequency and severity of prior period liability claims were lower than expected and the effects of underwriting changes that affected these years have been more positive than expected, especially in the commercial excess liability class. Overall favorable development of about $310 million was experienced in the professional liability classes other than fidelity. The most significant amount of favorable development occurred in the directors and officers liability class, particularly from our business outside the United States, with additional favorable development in the fiduciary liability class, partially offset by adverse development experienced in the errors and omissions liability class. The aggregate reported loss activity related to accident years 2008 and prior was less than expected. Favorable development of about $80 million in the aggregate was experienced in the personal and commercial property classes, primarily related to the 2009 and 2010 accident years. The severity and frequency of late developing property claims that emerged during 2011 were lower than expected. Unfavorable development of about $70 million was experienced in the fidelity class due to higher than expected reported loss emergence, related to the 2010 accident year and, to a lesser extent, the 2009 accident year. Favorable development of about $30 million was experienced in the personal automobile business due primarily to lower than expected frequency of prior year claims. Favorable development of about $30 million was experienced in the runoff of the reinsurance assumed business due primarily to better than expected reported loss activity from cedants. Favorable development of about $15 million was experienced in the surety business due to lower than expected loss emergence in recent accident years.
	(c)  The estimation of loss reserves relating to asbestos and toxic waste claims on insurance policies written many years ago is subject to greater uncertainty than other types of claims due to inconsistent court decisions as well as judicial interpretations and legislative actions that in some instances have tended to broaden coverage beyond the original intent of such policies and in others have expanded theories of liability. The insurance industry as a whole is engaged in extensive litigation over coverage, accident year allocation and liability issues and is thus confronted with a continuing uncertainty in its efforts to quantify these exposures.
	Asbestos remains the most significant and difficult mass tort for the insurance industry in terms of claims volume and dollar exposure. Asbestos claims relate primarily to bodily injuries asserted by those who came in contact with asbestos or products containing asbestos. Tort theory affecting asbestos litigation has evolved over the years. Early court cases established the “continuous trigger” theory with respect to insurance coverage. Under this theory, insurance coverage is deemed to be triggered from the time a claimant is first exposed to asbestos until the manifestation of any disease. This interpretation of a policy trigger can involve insurance policies over many years and increases insurance companies’ exposure to liability.
	New asbestos claims and new exposures on existing claims have continued despite the fact that usage of asbestos has declined since the mid-1970s. Many claimants were exposed to multiple asbestos products over an extended period of time. As a result, claim filings typically name dozens of defendants. The plaintiffs’ bar has solicited new claimants through extensive advertising and through asbestos medical screenings. A vast majority of asbestos bodily injury claims have been filed by claimants who do not show any signs of asbestos related disease. New asbestos cases are often filed in those jurisdictions with a reputation for judges and juries that are sympathetic to plaintiffs.
	Approximately 100 manufacturers and distributors of asbestos products have filed for bankruptcy protection as a result of asbestos related liabilities. A bankruptcy sometimes involves an agreement to a plan between the debtor and its creditors, including the creation of a trust to pay current and future asbestos claimants for their injuries. Although the debtor is negotiating in part with its insurers’ money, insurers are generally given only limited opportunity to be heard. In addition to contributing to the overall number of claims, bankruptcy proceedings not only result in increased settlement demands against remaining solvent defendants, but also create the potential for recoveries from multiple trusts by the same claimant for the same alleged injuries.
	There have been some positive legislative and judicial developments in the asbestos environment over the past several years. Various challenges to the mass screening of claimants have been mounted which have led to higher medical evidentiary standards. Also, a number of states have implemented legislative and judicial reforms that focus the courts’ resources on the claims of the most seriously injured. Those who allege serious injury and can present credible evidence of their injuries are receiving priority trial settings in the courts, while those who have not shown any credible disease manifestation are having their hearing dates delayed or placed on an inactive docket, which preserves the right to pursue litigation in the future. Further, a number of key jurisdictions have adopted venue reform that requires plaintiffs to have a connection to the jurisdiction in order to file a complaint. In recognition that many aspects of bankruptcy plans are unfair to certain classes of claimants and to the insurance industry, these plans are being more closely scrutinized by the courts and rejected when appropriate. Finally, a number of jurisdictions have passed or are considering legislation that will require fuller disclosure by plaintiffs of amounts received from asbestos bankruptcy trusts.
	The P&C Group’s most significant individual asbestos exposures involve products liability on the part of “traditional” defendants who were engaged in the manufacture, distribution or installation of asbestos products. The P&C Group wrote excess liability and/or general liability coverages for these insureds. While these insureds are relatively few in number, their exposure has become substantial due to the increased volume of claims, the erosion of the underlying limits and the bankruptcies of target defendants.
	The P&C Group’s other asbestos exposures involve products and non-products liability on the part of “peripheral” defendants, including a mix of manufacturers, distributors and installers of certain products that contain asbestos in small quantities and owners or operators of properties where asbestos was present. Generally, these insureds are named defendants on a regional rather than a nationwide basis. As the financial resources of traditional asbestos defendants have been depleted, plaintiffs are targeting these viable peripheral parties with greater frequency and, in many cases, for large awards.
	Asbestos claims against the major manufacturers, distributors or installers of asbestos products were typically presented under the products liability section of primary general liability policies as well as under excess liability policies, both of which typically had aggregate limits that capped an insurer’s exposure. In recent years, a number of asbestos claims by insureds are being presented as “non-products” claims, such as those by installers of asbestos products and by property owners or operators who allegedly had asbestos on their property, under the premises or operations section of primary general liability policies. Unlike products exposures, these non-products exposures typically had no aggregate limits on coverage, creating potentially greater exposure. Further, in an effort to seek additional insurance coverage, some insureds with installation activities who have substantially eroded their products coverage are presenting new asbestos claims as non-products operations claims or attempting to reclassify previously settled products claims as non-products claims to restore a portion of previously exhausted products aggregate limits. It is difficult to predict whether insureds will be successful in asserting claims under non-products coverage or whether insurers will be successful in asserting additional defenses. Accordingly, the ultimate cost to insurers of the claims for coverage not subject to aggregate limits is uncertain.
	Various U.S. federal proposals to solve the ongoing asbestos litigation crisis have been considered by the U.S. Congress over the years, but none have yet been enacted. The prospect of federal asbestos reform legislation remains uncertain.
	In establishing asbestos reserves, the exposure presented by each insured is evaluated. As part of this evaluation, consideration is given to a variety of factors including the available insurance coverage; limits and deductibles; the jurisdictions involved; the number of claimants; the disease mix exhibited by the claimants; the past settlement values of similar claims; the potential role of other insurance, particularly underlying coverage below excess liability policies; potential bankruptcy impact; relevant judicial interpretations; and applicable coverage defenses, including asbestos exclusions.
	Significant uncertainty remains as to the ultimate liability of the P&C Group related to asbestos related claims. This uncertainty is due to several factors including the long latency period between asbestos exposure and disease manifestation and the resulting potential for involvement of multiple policy periods for individual claims; plaintiffs’ expanding theories of liability and increased focus on peripheral defendants; the volume of claims by unimpaired plaintiffs and the extent to which they can be precluded from making claims; the volume of claims by severely impaired plaintiffs, such as those with mesothelioma, and the size of settlements and judgments received by those plaintiffs; the volume of claims by plaintiffs suffering from other malignancies such as lung cancer and their ability to establish a causal link between their disease and exposure to asbestos; the efforts by insureds to claim the right to non-products coverage not subject to aggregate limits; the number of insureds seeking bankruptcy protection as a result of asbestos related liabilities; the ability of claimants to bring a claim in a state in which they have no residency or exposure; the impact of the exhaustion of primary limits and the resulting increase in claims on excess liability policies that the P&C Group has issued; inconsistent court decisions and diverging legal interpretations; and the possibility, however remote, of federal legislation that would address the asbestos problem. These significant uncertainties are not likely to be resolved in the near future.
	Toxic waste claims relate primarily to pollution and related cleanup costs. The P&C Group’s insureds have two potential areas of exposure: hazardous waste dump sites and pollution at the insured site primarily from underground storage tanks and manufacturing processes.
	The U.S. federal Comprehensive Environmental Response Compensation and Liability Act of 1980 (Superfund) has been interpreted to impose strict, retroactive and joint and several liability on potentially responsible parties (PRPs) for the cost of remediating hazardous waste sites. Most sites have multiple PRPs.
	Most PRPs named to date are parties who have been generators, transporters, past or present landowners or past or present site operators. Insurance policies issued to PRPs were not intended to cover claims arising from gradual pollution. Environmental remediation claims tendered by PRPs and others to insurers have frequently resulted in disputes over insurers’ contractual obligations with respect to pollution claims. The resulting litigation against insurers extends to issues of liability, coverage and other policy provisions.
	There is substantial uncertainty involved in estimating the P&C Group’s liabilities related to these claims. First, the liabilities of the claimants are extremely difficult to estimate. At any given waste site, the allocation of remediation costs among governmental authorities and the PRPs varies greatly depending on a variety of factors. Second, different courts have addressed liability and coverage issues regarding pollution claims and have reached inconsistent conclusions in their interpretation of several issues. These significant uncertainties are not likely to be resolved definitively in the near future.
	Uncertainties also remain as to the Superfund law itself. Superfund’s taxing authority expired on December 31, 1995 and has not been re-enacted. Federal legislation appears to be at a standstill. At this time, it is not possible to predict the direction that any reforms may take, when they may occur or the effect that any changes may have on the insurance industry.
	Without federal movement on Superfund reform, the enforcement of Superfund liability has occasionally shifted to the states. States are being forced to reconsider state-level cleanup statutes and regulations. As individual states move forward, the potential for conflicting state regulation becomes greater. In a few states, cases have been brought against insureds or directly against insurance companies for environmental pollution and natural resources damages. To date, only a few natural resource claims have been filed and they are being vigorously defended. Significant uncertainty remains as to the cost of remediating the state sites. Because of the large number of state sites, such sites could prove even more costly in the aggregate than Superfund sites.
	In establishing toxic waste reserves, the exposure presented by each insured is evaluated. As part of this evaluation, consideration is given to a variety of factors including: the probable liability, available insurance coverage, allocation of potential loss to the appropriate accident year, past settlement values of similar claims, relevant judicial interpretations, applicable coverage defenses as well as facts that are unique to each insured.
	Management believes that the loss reserves carried at December 31, 2013 for asbestos and toxic waste claims were adequate. However, given the judicial decisions and legislative actions that have broadened the scope of coverage and expanded theories of liability in the past and the possibilities of similar interpretations in the future, it is possible that the estimate of loss reserves relating to these exposures may increase in future periods as new information becomes available and as claims develop.

Debt_and_Credit_Arrangements

Debt and Credit Arrangements	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Debt and Credit Arrangements	'
	(6)  Debt and Credit Arrangements
	(a)   Long term debt consisted of the following:
		December 31
		2013		2012
		(in millions)
	5.2% notes due April 1, 2013	$	—	$	275
	5.75% notes due May 15, 2018		600		600
	6.6% debentures due August 15, 2018		100		100
	6.8% debentures due November 15, 2031		200		200
	6% notes due May 11, 2037		800		800
	6.5% notes due May 15, 2038		600		600
	6.375% capital securities due March 29, 2067		1,000		1,000
		$	3,300	$	3,575
	All of the outstanding notes and debentures are unsecured obligations of Chubb. Chubb generally may redeem some or all of the notes and debentures prior to maturity in accordance with the terms of each debt instrument.
	Chubb has outstanding $1.0 billion of unsecured junior subordinated capital securities. The capital securities will become due on April 15, 2037, the scheduled maturity date, but only to the extent that Chubb has received sufficient net proceeds from the sale of certain qualifying capital securities. Chubb must use its commercially reasonable efforts, subject to certain market disruption events, to sell enough qualifying capital securities to permit repayment of the capital securities on the scheduled maturity date or as soon thereafter as possible. Any remaining outstanding principal amount will be due on March 29, 2067, the final maturity date. The capital securities bear interest at a fixed rate of 6.375% through April 14, 2017. Thereafter, the capital securities will bear interest at a rate equal to the three-month LIBOR rate plus 2.25%. Subject to certain conditions, Chubb has the right to defer the payment of interest on the capital securities for a period not exceeding ten consecutive years. During any such period, interest will continue to accrue and Chubb generally may not declare or pay any dividends on or purchase any shares of its capital stock.
	In connection with the issuance of the capital securities, Chubb entered into a replacement capital covenant in which it agreed that it will not repay, redeem, or purchase the capital securities before March 29, 2047, unless, subject to certain limitations, it has received proceeds from the sale of specified replacement capital securities. The replacement capital covenant is not intended for the benefit of holders of the capital securities and may not be enforced by them. The replacement capital covenant is for the benefit of holders of one or more designated series of Chubb’s indebtedness, which will initially be its 6.8% debentures due November 15, 2031.
	Subject to the replacement capital covenant, the capital securities may be redeemed, in whole or in part, at any time on or after April 15, 2017 at a redemption price equal to the principal amount plus any accrued interest or prior to April 15, 2017 at a redemption price equal to the greater of (i) the principal amount or (ii) a make-whole amount, in each case plus any accrued interest.
	The amounts of long term debt due annually during the five years subsequent to December 31, 2013 are as follows:
	Years Ending December 31	(in millions)
	2014	$	—
	2015		—
	2016		—
	2017		—
	2018		700
	(b)  Interest costs of $213 million, $224 million and $245 million were incurred in 2013, 2012 and 2011, respectively. Interest paid was $213 million, $220 million and $244 million in 2013, 2012 and 2011, respectively.
	(c)  Chubb has a revolving credit agreement with a syndicate of banks that provides for up to $500 million of unsecured borrowings. The revolving credit facility is available for general corporate purposes. The agreement has a maturity date of September 24, 2017. Various interest rate options are available to Chubb, all of which are based on market interest rates. The agreement contains customary restrictive covenants, including a covenant to maintain a minimum adjusted consolidated shareholders’ equity. At December 31, 2013, Chubb was in compliance with all such covenants. Chubb is permitted to request an increase in the credit available under the agreement, no more than two times per year, up to a maximum facility amount of $750 million. Chubb is permitted to request on two occasions, at any time during the term of the agreement, an extension of the maturity date for an additional one year period. There have been no borrowings under this agreement. On the maturity date of the agreement, any borrowings then outstanding become payable.

Federal_and_Foreign_Income_Tax

Federal and Foreign Income Tax	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Federal and Foreign Income Tax	'
	(7)  Federal and Foreign Income Tax
	(a)  Income tax expense and taxes paid consisted of the following components:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Income tax expense
	Current tax
	United States	$	791		$	276		$	260
	Foreign		91			143			236
	Deferred tax, principally United States		10			32			25
		$	892		$	451		$	521
	Federal and foreign income taxes paid	$	789		$	472		$	598
	Income before federal and foreign income taxes from U.S. operations was $2,766 million, $1,373 million and $1,666 million in 2013, 2012 and 2011, respectively. Income before federal and foreign income taxes from foreign operations was $471 million, $623 million and $533 million in 2013, 2012 and 2011, respectively.
	(b)  The effective income tax rate is different than the statutory federal corporate tax rate. The reasons for the different effective tax rate were as follows:
		Years Ended December 31
		2013						2012						2011
		Amount			% of			Amount			% of			Amount			% of
					Pre-Tax						Pre-Tax						Pre-Tax
					Income						Income						Income
		(in millions)
	Income before federal and foreign income tax	$	3,237					$	1,996					$	2,199
	Tax at statutory federal income tax rate	$	1,133			35	%	$	699			35	%	$	770			35	%
	Tax exempt interest income		(222	)		(6.8	)		(233	)		(11.7	)		(243	)		(11.0	)
	Other, net		(19	)		(.6	)		(15	)		(.7	)		(6	)		(.3	)
	Federal and foreign income tax	$	892			27.6	%	$	451			22.6	%	$	521			23.7	%
	(c)  The tax effects of temporary differences that gave rise to deferred income tax assets and liabilities were as follows:
		December 31
		2013			2012
		(in millions)
	Deferred income tax assets
	Unpaid losses and loss expenses	$	524		$	605
	Unearned premiums		350			341
	Foreign tax credits		867			870
	Employee compensation		142			119
	Postretirement benefits		95			324
	Other-than-temporary impairment losses		291			294
	Total		2,269			2,553
	Deferred income tax liabilities
	Deferred policy acquisition costs		356			341
	Unremitted earnings of foreign subsidiaries		970			951
	Unrealized appreciation of investments		660			1,084
	Other invested assets		184			225
	Other, net		52			114
	Total		2,222			2,715
	Net deferred income tax asset (liability)	$	47		$	(162	)
	Deferred income tax assets were established related to the expected future U.S. tax benefit of losses incurred by a foreign subsidiary of the Corporation. Realization of these deferred tax assets depends on the subsidiary’s ability to generate sufficient taxable income in future periods. A valuation allowance of $13 million and $12 million was recorded at December 31, 2013 and 2012, respectively, to reflect management’s assessment that the realization of a portion of the deferred tax assets is uncertain due to the inability of the foreign subsidiary to generate sufficient taxable income in the near term. Although realization of the remaining deferred tax assets is not assured, management believes it is more likely than not that such deferred tax assets will be realized.
	(d)  Chubb and its U.S. subsidiaries file a consolidated federal income tax return with the U.S. Internal Revenue Service (IRS). The Corporation also files income tax returns with various state and foreign tax authorities. The U.S. income tax returns for years prior to 2010 are no longer subject to examination by the IRS. The examination of the U.S. income tax returns for 2010 and 2011 is expected to be completed in 2014. Management does not anticipate any assessments for tax years that remain subject to examination that would have a material effect on the Corporation’s financial position or results of operations.

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2013
Insurance [Abstract]	'
Reinsurance	'
	(8)  Reinsurance
	In the ordinary course of business, the P&C Group assumes and cedes reinsurance with other insurance companies. Reinsurance is ceded to provide greater diversification of risk and to limit the P&C Group’s maximum net loss arising from large risks or catastrophic events.
	A large portion of the P&C Group’s ceded reinsurance is effected under contracts known as treaties under which all risks meeting prescribed criteria are automatically covered. Most of these arrangements consist of excess of loss and catastrophe contracts that protect against a specified part or all of certain types of losses over stipulated amounts arising from any one occurrence or event. In certain circumstances, reinsurance is also effected by negotiation on individual risks.
	Ceded reinsurance contracts do not relieve the P&C Group of the primary obligation to its policyholders. Thus, an exposure exists with respect to reinsurance ceded to the extent that any reinsurer is unable or unwilling to meet its obligations assumed under the reinsurance contracts. The P&C Group monitors the financial strength of its reinsurers on an ongoing basis.
	Premiums earned and insurance losses and loss expenses are reported net of reinsurance in the consolidated statements of income.
	The effect of reinsurance on the premiums written and earned of the P&C Group was as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Direct premiums written	$	12,804		$	12,647		$	12,452
	Assumed reinsurance		503			423			398
	Ceded reinsurance		(1,083	)		(1,200	)		(1,092	)
	Net premiums written	$	12,224		$	11,870		$	11,758
	Direct premiums earned	$	12,717		$	12,596		$	12,387
	Assumed reinsurance		476			422			365
	Ceded reinsurance		(1,127	)		(1,180	)		(1,108	)
	Net premiums earned	$	12,066		$	11,838		$	11,644
	Ceded losses and loss expenses, which reduce losses and loss expenses incurred, were $400 million, $586 million and $308 million in 2013, 2012, and 2011, respectively.

StockBased_Employee_Compensati

Stock-Based Employee Compensation Plans	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock-Based Employee Compensation Plans	'
	(9)  Stock-Based Employee Compensation Plans
	The Corporation has a stock-based employee compensation plan, The Chubb Corporation Long-Term Incentive Plan. The compensation cost with respect to the plan was $89 million, $84 million and $82 million in 2013, 2012 and 2011, respectively. The total income tax benefit included in net income with respect to the stock-based compensation arrangement was $31 million in 2013 and $29 million in both 2012 and 2011.
	As of December 31, 2013, there was $80 million of unrecognized compensation cost related to nonvested awards. That cost is expected to be reflected in operating results over a weighted average period of 1.8 years.
	The Long-Term Incentive Plan provides for the granting of restricted stock units, restricted stock, performance units, stock options and other stock-based awards to the Corporation’s employees. The maximum number of shares of Chubb’s common stock with respect to which stock-based awards may be granted under the plan most recently approved by shareholders is 8,650,000 shares. Additional shares of Chubb’s common stock may also become available for grant in connection with the cancellation, forfeiture and/or settlement of awards previously granted. At December 31, 2013, 6,891,434 shares were available for grant.
	Restricted Stock Units, Performance Units and Restricted Stock
	Restricted stock unit awards are payable in cash, in shares of Chubb’s common stock or in a combination of both. Restricted stock units are not considered to be outstanding shares of common stock, have no voting rights and are subject to forfeiture during the restriction period. Holders of restricted stock units may receive dividend equivalents. Performance unit awards are based on the achievement of performance goals over three year performance periods. Performance unit awards are payable in cash, in shares of Chubb’s common stock or in a combination of both. Restricted stock awards consist of shares of Chubb’s common stock granted at no cost to the employees. Shares of restricted stock become outstanding when granted, receive dividends and have voting rights. The shares are subject to forfeiture and to restrictions that prevent their sale or transfer during the restriction period.
	An amount equal to the fair value at the date of grant of restricted stock unit awards and performance unit awards is expensed over the vesting period. The weighted average fair value per share of the restricted stock units granted was $83.75, $68.64 and $60.58 in 2013, 2012 and 2011, respectively. The weighted average fair value per share of the performance units granted was $98.46, $63.38 and $64.34 in 2013, 2012 and 2011, respectively.
	Additional information with respect to restricted stock units and performance units is as follows:
			Restricted Stock Units					Performance Units*
			Number			Weighted Average		Number			Weighted Average
			of Shares			Grant Date		of Shares			Grant Date
						Fair Value					Fair Value
	Nonvested, January 1, 2013			2,418,946		$	59.54		973,909		$	63.88
	Granted			668,754			83.75		408,989			98.46
	Vested**			(852,786	)		51.42		(500,409	)		64.34
	Forfeited			(107,267	)		63		(21,348	)		70.58
	Nonvested, December 31, 2013			2,127,647			70.23		861,141			79.87
		*	The number of shares earned may range from 0% to 200% of the performance units shown in the table above.
		**	The performance units earned in 2013 were 132.6% of the vested shares shown in the table, or 663,542 shares.
	The total fair value of restricted stock units that vested during 2013, 2012 and 2011 was $72 million, $74 million and $59 million, respectively. The total fair value of performance units that vested during 2013, 2012 and 2011 was $64 million, $70 million and $47 million, respectively.
	Stock Options
	Stock options are granted at exercise prices not less than the fair value of Chubb’s common stock on the date of grant. The terms and conditions upon which options become exercisable may vary among grants. Options expire no later than ten years from the date of grant.
	An amount equal to the fair value of stock options at the date of grant is expensed over the vesting period. The weighted average fair value per stock option granted during 2013, 2012 and 2011 was $14.95, $11.95 and $11.55, respectively. The fair value of each stock option was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions:
			2013			2012		2011
	Risk-free interest rate			0.90%			1.00%		2.40%
	Expected volatility			24.40%			24.60%		24.20%
	Dividend yield			2.10%			2.40%		2.60%
	Expected average term (in years)			5.5			5.5		5.5
	Additional information with respect to stock options is as follows:
			Number			Weighted		Weighted Average			Aggregate
			of Shares			Average		Remaining			Intrinsic Value
						Exercise Price		Contractual Term
								(in years)			(in millions)
	Outstanding, January 1, 2013			520,575		$	40.24
	Granted			71,903			83.89
	Exercised			(317,256	)		32.48
	Forfeited			(23,535	)		39.94
	Outstanding, December 31, 2013			251,687			62.52		6.6		$	9
	Exercisable, December 31, 2013			127,475			48.93		4.7			6
	The total intrinsic value of the stock options exercised during 2013, 2012 and 2011 was $16 million, $40 million and $35 million, respectively. The Corporation received cash of $10 million, $47 million and $53 million during 2013, 2012 and 2011, respectively, from the exercise of stock options. The tax benefit realized with respect to the exercise of stock options was $5 million, $13 million and $11 million during 2013, 2012 and 2011, respectively.

Employee_Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2013
Compensation And Retirement Disclosure [Abstract]	'
Employee Benefits	'
	(10) Employee Benefits
	(a)  The Corporation has several non-contributory defined benefit pension plans covering substantially all employees. Prior to 2001, benefits were generally based on an employee’s years of service and average compensation during the last five years of employment. Effective January 1, 2001, the Corporation changed the formula for providing pension benefits from the final average pay formula to a cash balance formula. Under the cash balance formula, a notional account is established for each employee, which is credited semi-annually with an amount equal to a percentage of eligible compensation based on age and years of service plus interest based on the account balance. Employees hired prior to 2001 will generally be eligible to receive vested benefits based on the higher of the final average pay or cash balance formulas.
	The Corporation’s funding policy is to contribute amounts that meet regulatory requirements plus additional amounts determined by management based on actuarial valuations, market conditions and other factors. This may result in no contribution being made in a particular year.
	The Corporation also provides certain other postretirement benefits, principally health care and life insurance, to retired employees and their beneficiaries and covered dependents. Substantially all employees hired before January 1, 1999 may become eligible for these benefits upon retirement if they meet minimum age and years of service requirements. Health care coverage is contributory. Retiree contributions vary based upon a retiree’s age, type of coverage and years of service with the Corporation. Life insurance coverage is non-contributory.
	The Corporation funds a portion of the health care benefits obligation where such funding can be accomplished on a tax effective basis. Benefits are paid as covered expenses are incurred.
	The funded status of the pension and other postretirement benefit plans at December 31, 2013 and 2012 was as follows:
		Pension						Other
		Benefits						Postretirement
								Benefits
		2013			2012			2013			2012
		(in millions)
	Benefit obligation, beginning of year	$	2,894		$	2,494		$	470		$	454
	Service cost		95			88			13			12
	Interest cost		125			124			19			20
	Actuarial loss (gain)		(261	)		256			(97	)		(4	)
	Benefits paid		(75	)		(74	)		(11	)		(12	)
	Foreign currency translation effect		(1	)		6			—			—
	Benefit obligation, end of year		2,777			2,894			394			470
	Plan assets at fair value		2,717			2,305			130			96
	Funded status at end of year, included in other liabilities	$	60		$	589		$	264		$	374
	Net actuarial loss (gain) and prior service cost included in accumulated other comprehensive income that were not yet recognized as components of net benefit costs at December 31, 2013 and 2012 were as follows:
		Pension						Other
		Benefits						Postretirement
								Benefits
		2013			2012			2013			2012
		(in millions)
	Net actuarial loss (gain)	$	396		$	989		$	(13	)	$	108
	Prior service cost		16			18			1			—
		$	412		$	1,007		$	(12	)	$	108
	The accumulated benefit obligation for the pension plans was $2,381 million and $2,479 million at December 31, 2013 and 2012, respectively. The accumulated benefit obligation is the present value of pension benefits earned as of the measurement date based on employee service and compensation prior to that date. It differs from the pension benefit obligation in the table on the previous page in that the accumulated benefit obligation includes no assumptions regarding future compensation levels.
	The weighted average assumptions used to determine the benefit obligations were as follows:
		Pension Benefits						Other
								Postretirement
								Benefits
		2013			2012			2013			2012
	Discount rate		5.2	%		4.4	%		5.2	%		4.4	%
	Rate of compensation increase		4.5			4.5			—			—
	The Corporation made pension plan contributions of $74 million and $98 million during 2013 and 2012, respectively. The Corporation made other postretirement benefit plan contributions of $10 million during both 2013 and 2012.
	The components of net pension and other postretirement benefit costs reflected in net income and other changes in plan assets and benefit obligations recognized in other comprehensive income for the years ended December 31, 2013, 2012 and 2011 were as follows:
		Pension Benefits									Other
											Postretirement Benefits
		2013			2012			2011			2013			2012			2011
		(in millions)
	Costs reflected in net income
	Service cost	$	95		$	88		$	79		$	13		$	12		$	11
	Interest cost		125			124			120			19			20			22
	Expected return on plan assets		(165	)		(155	)		(140	)		(7	)		(6	)		(5	)
	Amortization of net actuarial loss and prior service cost and other		90			80			68			3			3			3
		$	145		$	137		$	127		$	28		$	29		$	31
	Changes in plan assets and benefit obligations recognized in other comprehensive income
	Net actuarial loss (gain)	$	(505	)	$	139		$	355		$	(117	)	$	(11	)	$	45
	Amortization of net actuarial loss and prior service cost and other		(90	)		(80	)		(68	)		(3	)		(3	)		(3	)
		$	(595	)	$	59		$	287		$	(120	)	$	(14	)	$	42
	The estimated aggregate net actuarial loss and prior service cost that will be amortized from accumulated other comprehensive income into net benefit costs during 2014 for the pension and other postretirement benefit plans is $34 million.
	The weighted average assumptions used to determine net pension and other postretirement benefit costs were as follows:
		Pension Benefits									Other
											Postretirement Benefits
		2013			2012			2011			2013			2012			2011
	Discount rate		4.40%			5.00%			5.75%			4.40%			5.00%			5.75%
	Rate of compensation increase		4.5			4.5			4.5			—			—			—
	Expected long term rate of return on plan assets		7.5			7.75			7.75			7.5			7.75			7.75
	The weighted average health care cost trend rate assumptions used to measure the expected cost of medical benefits were as follows:
		December 31
	2013			2012
Health care cost trend rate for next year		7.6	%		7.9	%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		4.5			4.5
Year that the rate reaches the ultimate trend rate		2028			2028
The health care cost trend rate assumption has a significant effect on the amount of the accumulated other postretirement benefit obligation and the net other postretirement benefit cost reported. To illustrate, a one percent increase in the trend rate for each year would increase the accumulated other postretirement benefit obligation at December 31, 2013 by approximately $67 million and the aggregate of the service and interest cost components of net other postretirement benefit cost for the year ended December 31, 2013 by approximately $6 million. A one percent decrease in the trend rate for each year would decrease the accumulated other postretirement benefit obligation at December 31, 2013 by approximately $53 million and the aggregate of the service and interest cost components of net other postretirement benefit cost for the year ended December 31, 2013 by approximately $5 million.
The long term objective of the pension plan is to provide sufficient funding to cover expected benefit obligations, while assuming a prudent level of portfolio risk. The assets of the pension plan are invested, either directly or through pooled funds, in a diversified portfolio of predominately U.S. equity securities and fixed maturities. The Corporation seeks to obtain a rate of return that over time equals or exceeds the returns of the broad markets in which the plan assets are invested. The target allocation of plan assets is 55% to 65% invested in equity securities, with the remainder primarily invested in fixed maturities. The Corporation rebalances its pension assets to the target allocation as market conditions permit. The Corporation determined the expected long term rate of return assumption for each asset class based on an analysis of the historical returns and the expectations for future returns. The expected long term rate of return for the portfolio is a weighted aggregation of the expected returns for each asset class.
The fair values of the pension plan assets were as follows:
	December 31
	2013			2012
	(in millions)
Short term investments	$	37		$	33
Fixed maturities
U.S. government and government agency and authority obligations		224			239
Corporate bonds		371			321
Foreign government and government agency obligations		104			80
Mortgage-backed securities		217			174
Total fixed maturities		916			814
Equity securities		1,718			1,404
Other assets		46			54
	$	2,717		$	2,305
At December 31, 2013 and 2012, pension plan assets invested in pooled funds had a fair value of $1,425 million and $1,200 million, respectively.
At December 31, 2013 and 2012, other postretirement benefit plan assets were invested in pooled funds and had a fair value of $130 million and $96 million, respectively.
The estimated benefits expected to be paid in each of the next five years and in the aggregate for the following five years are as follows:
Years Ending December 31	Pension			Other
	Benefits			Postretirement
				Benefits
	(in millions)
2014	$	99		$	12
2015		104			13
2016		114			15
2017		149			16
2018		130			18
2019-2023		803			114
(b)  The Corporation has a defined contribution benefit plan, the Capital Accumulation Plan, in which substantially all employees are eligible to participate. Under this plan, the employer makes an annual matching contribution equal to 100% of each eligible employee’s pre-tax elective contributions, up to 4% of the employee’s eligible compensation. Contributions are invested at the election of the employee in Chubb’s common stock or in various other investment funds. The expense recognized with respect to the plan was $29 million, $26 million and $27 million in 2013, 2012 and 2011, respectively.

Comprehensive_Income

Comprehensive Income	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Comprehensive Income	'
	(11)  Comprehensive Income
	Comprehensive income is defined as all changes in shareholders’ equity, except those arising from transactions with shareholders. Comprehensive income includes net income and other comprehensive income or loss, which for the Corporation consists of changes in unrealized appreciation or depreciation of investments carried at fair value, changes in unrealized other-than-temporary impairment losses of fixed maturities, changes in postretirement benefit costs not yet recognized in net income and changes in foreign currency translation gains or losses.
	The components of other comprehensive income or loss were as follows:
			Years Ended December 31
			2013									2012									2011
			Before			Income			Net of			Before			Income			Net of			Before			Income			Net of
			Tax			Tax			Tax			Tax			Tax			Tax			Tax			Tax			Tax
												(in millions)
	Net unrealized holding gains (losses) arising		$	(1,000	)	$	(350	)	$	(650	)	$	556		$	195		$	361		$	1,029		$	359		$	670
	during the year
	Unrealized other-than-temporary			—			—			—			(2	)		(1	)		(1	)		(1	)		—			(1	)
	impairment losses arising during the year
	Reclassification adjustment for net realized			212			74			138			127			44			83			81			28			53
	gains included in net income
	Net unrealized gains (losses) recognized in other comprehensive income or loss			(1,212	)		(424	)		(788	)		427			150			277			947			331			616
	Postretirement benefit gain (loss) not yet			622			218			404			(128	)		(45	)		(83	)		(400	)		(140	)		(260	)
	recognized in net income arising during the year
	Reclassification adjustment for the			(93	)		(33	)		(60	)		(83	)		(30	)		(53	)		(71	)		(26	)		(45	)
	amortization of net actuarial loss and prior service cost included in net income (a)
	Net change in postretirement benefit			715			251			464			(45	)		(15	)		(30	)		(329	)		(114	)		(215	)
	costs not yet recognized in net income
	Foreign currency translation gains (losses)			(111	)		(39	)		(72	)		(16	)		(5	)		(11	)		6			2			4
	Total other comprehensive income (loss)		$	(608	)	$	(212	)	$	(396	)	$	366		$	130		$	236		$	624		$	219		$	405
	(a)	Postretirement benefit costs recognized in net income during the period are included among several of the loss and expense components presented in the consolidated statements of income.

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingent Liabilities	'
	(12)  Commitments and Contingent Liabilities
	(a)  Chubb Financial Solutions (CFS), a wholly owned subsidiary of Chubb, participated in derivative financial instruments and has been in runoff since 2003. At December 31, 2013, CFS’s remaining derivative contracts were insignificant.
	CFS’s aggregate exposure, or retained risk, from its derivative contracts is referred to as notional amount. Notional amounts are used to calculate the exchange of contractual cash flows and are not necessarily representative of the potential for gain or loss. Notional amounts are not recorded on the balance sheet. The notional amount of future obligations under CFS’s derivative contracts at December 31, 2013 and 2012 was approximately $80 million and $90 million, respectively.
	Future obligations with respect to the derivative contracts are carried at fair value at the balance sheet date and are included in other liabilities. The fair value of future obligations under CFS’s derivative contracts at both December 31, 2013 and 2012 was approximately $2 million.
	(b)  A property and casualty insurance subsidiary issued a reinsurance contract to an insurer that provides financial guarantees on debt obligations. At December 31, 2013, the aggregate principal commitments related to this contract for which the subsidiary was contingently liable amounted to approximately $380 million. These commitments expire by 2023.
	(c)  The Corporation occupies office facilities under lease agreements that expire at various dates through 2029; such leases are generally renewed or replaced by other leases. Most facility leases contain renewal options for increments ranging from two to ten years. The Corporation also leases data processing, office and transportation equipment. All leases are operating leases.
	Rent expense was as follows:
		Years Ended
		December 31
		2013		2012		2011
		(in millions)
	Office facilities	$	71	$	71	$	73
	Equipment		13		11		10
		$	84	$	82	$	83
	At December 31, 2013, future minimum rental payments required under non-cancellable operating leases were as follows:
	Years Ending December 31	(in millions)
	2014	$	67
	2015		59
	2016		47
	2017		37
	2018		32
	After 2018		74
		$	316
	(d)  The Corporation had commitments totaling $660 million at December 31, 2013 to fund limited partnership investments. These commitments can be called by the partnerships (generally over a period of 5 years or less) to fund certain partnership expenses or the purchase of investments.

Segments_Information

Segments Information	12 Months Ended
	Dec. 31, 2013
Segment Reporting [Abstract]	'
Segments Information	'
	(13)  Segments Information
	The principal business of the Corporation is the sale of property and casualty insurance. The profitability of the property and casualty insurance business depends on the results of both underwriting operations and investments, which are viewed as two distinct operations. The underwriting operations are managed and evaluated separately from the investment function.
	The P&C Group underwrites most lines of property and casualty insurance. Underwriting operations consist of four separate business units: personal insurance, commercial insurance, specialty insurance and reinsurance assumed. The personal segment targets the personal insurance market. The personal classes include automobile, homeowners and other personal coverages. The commercial segment includes those classes of business that are generally available in broad markets and are of a more commodity nature. Commercial classes include multiple peril, casualty, workers’ compensation and property and marine. The specialty segment includes those classes of business that are available in more limited markets since they require specialized underwriting and claim settlement. Specialty classes include professional liability coverages and surety. The reinsurance assumed business has been in runoff since the transfer of the ongoing reinsurance assumed business to a reinsurance company in 2005.
	Corporate and other includes investment income earned on corporate invested assets, corporate expenses and the results of the Corporation’s non-insurance subsidiaries.
	Performance of the property and casualty underwriting segments is measured based on statutory underwriting results. Statutory underwriting profit is arrived at by reducing premiums earned by losses and loss expenses incurred and statutory underwriting expenses incurred. Under statutory accounting principles applicable to property and casualty insurance companies, policy acquisition and other underwriting expenses are recognized immediately, not at the time premiums are earned.
	Management uses underwriting results determined in accordance with GAAP to assess the overall performance of the underwriting operations. Underwriting income determined in accordance with GAAP is defined as premiums earned less losses and loss expenses incurred and GAAP underwriting expenses incurred. To convert statutory underwriting results to a GAAP basis, certain policy acquisition expenses are deferred and amortized over the period in which the related premiums are earned.
	Investment income performance is measured based on investment income net of investment expenses, excluding realized investment gains and losses.
	Distinct investment portfolios are not maintained for each underwriting segment. Property and casualty invested assets are available for payment of losses and expenses for all classes of business. Therefore, such assets and the related investment income are not allocated to underwriting segments.
	Revenues, income before income tax and assets of each operating segment were as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Revenues
	Property and casualty insurance
	Premiums earned
	Personal insurance	$	4,214		$	4,024		$	3,917
	Commercial insurance		5,237			5,144			4,945
	Specialty insurance		2,618			2,666			2,769
	Total insurance		12,069			11,834			11,631
	Reinsurance assumed		(3	)		4			13
			12,066			11,838			11,644
	Investment income		1,436			1,518			1,598
	Total property and casualty insurance		13,502			13,356			13,242
	Corporate and other		43			46			55
	Realized investment gains, net		402			193			288
	Total revenues	$	13,947		$	13,595		$	13,585
	Income (loss) before income tax
	Property and casualty insurance
	Underwriting
	Personal insurance	$	509		$	192		$	47
	Commercial insurance		692			44			1
	Specialty insurance		406			262			427
	Total insurance		1,607			498			475
	Reinsurance assumed		9			47			36
			1,616			545			511
	Increase in deferred policy acquisition costs		59			3			63
	Underwriting income		1,675			548			574
	Investment income		1,391			1,482			1,562
	Other income		6			10			21
	Total property and casualty insurance		3,072			2,040			2,157
	Corporate and other		(237	)		(237	)		(246	)
	Realized investment gains, net		402			193			288
	Total income before income tax	$	3,237		$	1,996		$	2,199
		December 31
		2013			2012			2011
		(in millions)
	Assets
	Property and casualty insurance	$	48,278		$	49,441		$	48,017
	Corporate and other		2,248			2,830			2,513
	Adjustments and eliminations		(93	)		(87	)		(85	)
	Total assets	$	50,433		$	52,184		$	50,445
	The international business of the property and casualty insurance segments is conducted primarily through subsidiaries that operate solely outside of the United States. Their assets and liabilities are located principally in the countries where the insurance risks are written. International business is also written by branch offices of a U.S. subsidiary.
	Revenues of the P&C Group by geographic area were as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Revenues
	United States	$	10,205		$	9,996		$	9,831
	International		3,297
						3,360			3,411
	Total	$	13,502		$	13,356		$	13,242

Fair_Values_of_Financial_Instr

Fair Values of Financial Instruments	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
Fair Values of Financial Instruments	'
	(14)  Fair Values of Financial Instruments
	(a)  Fair values of financial instruments are determined by management using valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Fair values are generally measured using quoted prices in active markets for identical assets or liabilities or other inputs, such as quoted prices for similar assets or liabilities, that are observable either directly or indirectly. In those instances where observable inputs are not available, fair values are measured using unobservable inputs for the asset or liability. Unobservable inputs reflect the Corporation’s own assumptions about the assumptions that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. Fair value estimates derived from unobservable inputs are affected by the assumptions used, including the discount rates and the estimated amounts and timing of future cash flows. The derived fair value estimates cannot be substantiated by comparison to independent markets and are not necessarily indicative of the amounts that would be realized in a current market exchange. Certain financial instruments, particularly insurance contracts, are excluded from fair value disclosure requirements.
	The methods and assumptions used to estimate the fair values of financial instruments are as follows:
	(i)  The carrying value of short term investments approximates fair value due to the short maturities of these investments.
	(ii)  Fair values of fixed maturities are determined by management, utilizing prices obtained from a third party, nationally recognized pricing service or, in the case of securities for which prices are not provided by a pricing service, from third party brokers. For fixed maturities that have quoted prices in active markets, market quotations are provided. For fixed maturities that do not trade on a daily basis, the pricing service and brokers provide fair value estimates using a variety of inputs including, but not limited to, benchmark yields, reported trades, broker/dealer quotes, issuer spreads, bids, offers, reference data, prepayment rates and measures of volatility. Management reviews on an ongoing basis the reasonableness of the methodologies used by the relevant pricing service and brokers. In addition, management, using the prices received for the securities from the pricing service and brokers, determines the aggregate portfolio price performance and reviews it against applicable indices. If management believes that significant discrepancies exist, it will discuss these with the relevant pricing service or broker to resolve the discrepancies.
	(iii)  Fair values of equity securities are determined by management, utilizing quoted market prices.
	(iv)  Fair values of warrants included in other invested assets are determined by management, utilizing an option pricing model.
	(v)  Fair values of long term debt issued by Chubb are determined by management, utilizing prices obtained from a third party, nationally recognized pricing service.
	The carrying values and fair values of financial instruments were as follows:
		December 31
		2013				2012
		Carrying		Fair		Carrying		Fair
		Value		Value		Value		Value
		(in millions)
	Assets
	Invested assets
	Short term investments	$	2,114	$	2,114	$	2,528	$	2,528
	Fixed maturities (Note 2)		37,091		37,091		38,076		38,076
	Equity securities		1,810		1,810		1,663		1,663
	Other invested assets		—		—		46		46
	Liabilities
	Long term debt (Note 6)		3,300		3,806		3,575		4,372
	At December 31, 2013 and 2012, a pricing service provided fair value amounts for approximately 99% of the Corporation’s fixed maturities. The prices obtained from a pricing service and brokers generally are non-binding, but are reflective of current market transactions in the applicable financial instruments.
	At December 31, 2013 and 2012, the Corporation held an insignificant amount of financial instruments in its investment portfolio for which a lack of market liquidity impacted the determination of fair value.
	The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three broad levels as follows:
	Level 1 —	Unadjusted quoted prices in active markets for identical financial instruments.
	Level 2 —	Other inputs that are observable for the financial instrument, either directly or indirectly.
	Level 3 —	Significant unobservable inputs.
	The fair value of financial instruments categorized based upon the lowest level of input that was significant to the fair value measurement was as follows:
		December 31, 2013
		Level 1		Level 2		Level 3		Total
		(in millions)
	Assets
	Short term investments	$	399	$	1,715	$	—	$	2,114
	Fixed maturities
	Tax exempt		—		18,416		5		18,421
	Taxable
	U.S. government and government agency and authority obligations		—		802		—		802
	Corporate bonds		—		9,179		135		9,314
	Foreign government and government agency obligations		—		6,881		9		6,890
	Residential mortgage-backed securities		—		293		6		299
	Commercial mortgage-backed securities		—		1,345		20		1,365
			—		18,500		170		18,670
	Total fixed maturities		—		36,916		175		37,091
	Equity securities		1,803		—		7		1,810
		$	2,202	$	38,631	$	182	$	41,015
	Liabilities
	Long term debt	$	—	$	3,806	$	—	$	3,806
		December 31, 2012
		Level 1		Level 2		Level 3		Total
		(in millions)
	Assets
	Short term investments	$	182	$	2,346	$	—	$	2,528
	Fixed maturities
	Tax exempt		—		19,907		6		19,913
	Taxable
	U.S. government and government agency and authority obligations		—		1,039		—		1,039
	Corporate bonds		—		7,779		158		7,937
	Foreign government and government agency obligations		—		7,008		—		7,008
	Residential mortgage-backed securities		—		446		9		455
	Commercial mortgage-backed securities		—		1,724		—		1,724
			—		17,996		167		18,163
	Total fixed maturities		—		37,903		173		38,076
Equity securities		1,655		—		8		1,663
Other invested assets		—		—		46		46
	$	1,837	$	40,249	$	227	$	42,313
Liabilities
Long term debt	$	—	$	4,372	$	—	$	4,372
(b)  The methods and assumptions used to estimate the fair value of the Corporation’s pension plan and other postretirement benefit plan assets, other than assets invested in pooled funds, are similar to the methods and assumptions used for the Corporation’s other financial instruments. The fair value of pooled funds is based on the net asset value of the funds.
Based on the fair value hierarchy, the fair value of the Corporation’s pension plan assets categorized based upon the lowest level of input that was significant to the fair value measurement was as follows:
	December 31, 2013
	Level 1		Level 2		Level 3		Total
	(in millions)
Short term investments	$	—	$	37	$	—	$	37
Fixed maturities
U.S. government and government agency and authority obligations		—		224		—		224
Corporate bonds		—		370		1		371
Foreign government and government agency obligations		—		104		—		104
Mortgage-backed securities		—		211		6		217
Total fixed maturities		—		909		7		916
Equity securities		573		1,145		—		1,718
Other assets		21		14		11		46
	$	594	$	2,105	$	18	$	2,717
	December 31, 2012
	Level 1		Level 2		Level 3		Total
	(in millions)
Short term investments	$	—	$	33	$	—	$	33
Fixed maturities
U.S. government and government agency and authority obligations		—		238		1		239
Corporate bonds		—		321		—		321
Foreign government and government agency obligations		—		79		1		80
Mortgage-backed securities		—		174		—		174
Total fixed maturities		—		812		2		814
Equity securities		457		947		—		1,404
Other assets		29		9		16		54
	$	486	$	1,801	$	18	$	2,305
The fair value of the Corporation’s other postretirement benefit plan assets was $130 million and $96 million at December 31, 2013 and 2012, respectively. Based on the fair value hierarchy, the fair value of these assets was categorized as Level 1 based upon the lowest level of input that was significant to the fair value measurement.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	(15)  Earnings Per Share
	Basic earnings per share is computed by dividing net income by the weighted average shares outstanding during the year. The computation of diluted earnings per share reflects the potential dilutive effect, using the treasury stock method, of outstanding awards under stock-based employee compensation plans.
	The following table sets forth the computation of basic and diluted earnings per share:
		Years Ended December 31
		2013		2012		2011
		(in millions except for per
		share amounts)
	Basic earnings per share:
	Net income	$	2,345	$	1,545	$	1,678
	Weighted average shares outstanding		258.2		269.5		289.3
	Basic earnings per share	$	9.08	$	5.73	$	5.8
	Diluted earnings per share:
	Net income	$	2,345	$	1,545	$	1,678
	Weighted average shares outstanding		258.2		269.5		289.3
	Additional shares from assumed issuance of shares under stock-based compensation awards		1.2		1.9		2.1
	Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share		259.4		271.4		291.4
	Diluted earnings per share	$	9.04	$	5.69	$	5.76

Shareholders_Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Shareholders' Equity	'
	(16)  Shareholders’ Equity
	(a)  The authorized but unissued preferred shares may be issued in one or more series and the shares of each series shall have such rights as fixed by the Board of Directors.
	(b)  The activity of Chubb’s common stock was as follows:
		Years Ended December 31
		2013			2012			2011
		(number of shares)
	Common stock issued
	Balance, beginning and end of year		371,980,460			371,980,460			371,980,460
	Treasury stock
	Balance, beginning of year		110,217,445			99,519,509			74,707,547
	Repurchase of shares		14,887,701			13,094,640			27,582,889
	Share activity under stock-based employee compensation plans		(1,431,177	)		(2,396,704	)		(2,770,927	)
	Balance, end of year		123,673,969			110,217,445			99,519,509
	Common stock outstanding, end of year		248,306,491			261,763,015			272,460,951
	(c)  As of December 31, 2013, $107 million remained under the share repurchase authorization that was approved by the Board of Directors on January 31, 2013. On January 30, 2014, the Board of Directors authorized the repurchase of up to $1.5 billion of Chubb’s common stock. These authorizations have no expiration date.
	(d)  The property and casualty insurance subsidiaries are required to file annual statements with insurance regulatory authorities prepared on an accounting basis prescribed or permitted by such authorities (statutory basis). For such subsidiaries, statutory accounting practices differ in certain respects from GAAP.
	A comparison of shareholders’ equity on a GAAP basis and policyholders’ surplus on a statutory basis is as follows:
		December 31
		2013						2012
		GAAP			Statutory			GAAP			Statutory
		(in millions)
	P&C Group	$	17,398		$	15,024		$	16,833		$	14,117
	Corporate and other		(1,301	)					(1,006	)
		$	16,097					$	15,827
	A comparison of GAAP and statutory net income (loss) is as follows:
		Years Ended December 31
		2013						2012					2011
		GAAP			Statutory			GAAP			Statutory		GAAP			Statutory
		(in millions)
	P&C Group	$	2,480		$	2,485		$	1,791		$	1,936	$	1,915		$	1,824
	Corporate and other		(135	)					(246	)				(237	)
		$	2,345					$	1,545				$	1,678
	At December 31, 2013, the aggregate statutory capital and surplus of the property and casualty insurance subsidiaries was $15.0 billion, of which $14.7 billion related to Federal Insurance Company (Federal). Federal is a direct subsidiary of Chubb and is the direct or indirect parent of most of Chubb’s other insurance subsidiaries. A risk-based capital formula is used by U.S. state regulatory authorities to identify insurance companies that may be undercapitalized and that may merit regulatory attention. The risk-based capital requirement level is calculated as two times the authorized control level risk-based capital and is the level at or below which company or state regulatory action would be required. At December 31, 2013, the risk-based capital requirement level for Federal was $4.9 billion.
	(e)  As a holding company, Chubb’s ability to continue to pay dividends to shareholders and to satisfy its obligations, including the payment of interest and principal on debt obligations, relies on the availability of liquid assets, which is dependent in large part on the dividend paying ability of its property and casualty insurance subsidiaries. The Corporation’s property and casualty insurance subsidiaries are subject to laws and regulations in the jurisdictions in which they operate that restrict the amount of dividends they may pay without the prior approval of regulatory authorities. The restrictions are generally based on net income and on certain levels of policyholders’ surplus as determined in accordance with statutory accounting practices. Dividends in excess of such thresholds are considered “extraordinary” and require prior regulatory approval. During 2013, these subsidiaries paid dividends of $1.6 billion to Chubb.
	The maximum dividend distribution that may be made by the property and casualty insurance subsidiaries to Chubb during 2014 without prior regulatory approval is approximately $2.0 billion.

Quarterly_Financial_Data

Quarterly Financial Data	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Quarterly Financial Data	'
	QUARTERLY FINANCIAL DATA
	Summarized unaudited quarterly financial data for 2013 and 2012 are shown below. In management’s opinion, the interim financial data contain all adjustments, consisting of normal recurring items, necessary to present fairly the results of operations for the interim periods.
			Three Months Ended
			March 31						June 30						September 30						December 31
			2013			2012			2013			2012			2013			2012			2013			2012(a)
			(in millions except for per share amounts)
	Revenues		$	3,517		$	3,410		$	3,551		$	3,423		$	3,403		$	3,362		$	3,476		$	3,400
	Losses and expenses			2,601			2,731			2,755			2,896			2,664			2,635			2,690			3,337
	Federal and foreign income			260			173			217			123			198			194			217			(39	)
	tax (credit)
	Net income		$	656		$	506		$	579		$	404		$	541		$	533		$	569		$	102
	Basic earnings per share		$	2.49		$	1.85		$	2.22		$	1.49		$	2.11		$	1.99		$	2.25		$	0.39
	Diluted earnings per share		$	2.48		$	1.83		$	2.21		$	1.48		$	2.1		$	1.98		$	2.24		$	0.38
	Underwriting ratios
	Losses to premiums earned			52.3	%		58	%		56.7	%		62.5	%		53	%		53.8	%		54.7	%		80.3	%
	Expenses to premiums written			32.3			32.2			32.1			31.3			32.7			32.5			30.8			30.9
	Combined			84.6	%		90.2	%		88.8	%		93.8	%		85.7	%		86.3	%		85.5	%		111.2	%
	(a)	In the fourth quarter of 2012, revenues were reduced by reinsurance reinstatement premium costs of $53 million and losses and expenses included net losses of $829 million related to Storm Sandy. Net income for the quarter was reduced by $573 million, or $2.15 of diluted earnings per share ($2.16 of basic earnings per share), for the after–tax effect of the net costs. Excluding the impact of Storm Sandy, the losses to premiums earned ratio was 50.9%, the expenses to premiums written ratio was 30.4% and the combined ratio was 81.3%.

Consolidated_Summary_of_Invest

Consolidated Summary of Investments - Other Than Investments in Related Parties	12 Months Ended
	Dec. 31, 2013
Summary Of Investments Other Than Investments In Related Parties [Abstract]	'
Consolidated Summary of Investments - Other Than Investments in Related Parties	'
	THE CHUBB CORPORATION
	Schedule I
	CONSOLIDATED SUMMARY OF INVESTMENTS — OTHER THAN INVESTMENTS IN RELATED PARTIES
	(in millions)
	December 31, 2013
	Type of Investment	Cost or		Fair		Amount
		Amortized		Value		at Which
		Cost				Shown in the
						Balance Sheet
	Short term investments	$	2,114	$	2,114	$	2,114
	Fixed maturities
	United States Government and government agencies and authorities		401		414		414
	States, municipalities and political subdivisions		18,191		18,809		18,809
	Foreign government and government agencies		6,719		6,890		6,890
	Public utilities		1,186		1,273		1,273
	All other corporate bonds		7,846		8,041		8,041
	Residential mortgage-backed securities		277		299		299
	Commercial mortgage-backed securities		1,339		1,365		1,365
	Total fixed maturities		35,959		37,091		37,091
	Equity securities
	Common stocks
	Public utilities		114		170		170
	Banks, trusts and insurance companies		88		156		156
	Industrial, miscellaneous and other		846		1,468		1,468
	Total common stocks		1,048		1,794		1,794
	Non-redeemable preferred stocks		9		16		16
	Total equity securities		1,057		1,810		1,810
	Other invested assets		1,598		1,598		1,598
	Total invested assets	$	40,728	$	42,613	$	42,613

Condensed_Financial_Informatio

Condensed Financial Information of Parent Company	12 Months Ended
	Dec. 31, 2013
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]	'
Condensed Financial Information of Parent Company	'
	Schedule II
	CONDENSED FINANCIAL INFORMATION OF REGISTRANT
	BALANCE SHEETS — PARENT COMPANY ONLY
	(in millions)
	December 31
		2013			2012
	Assets
	Invested Assets
	Short Term Investments	$	856		$	941
	Taxable Fixed Maturities (cost $1,095 and $1,273)		1,110			1,309
	Equity Securities (cost $ — and $176)		2			215
	Other Invested Assets		—			46
	TOTAL INVESTED ASSETS		1,968			2,511
	Investment in Consolidated Subsidiaries		17,455			16,900
	Other Assets		165			190
	TOTAL ASSETS	$	19,588		$	19,601
	Liabilities
	Long Term Debt	$	3,300		$	3,575
	Dividend Payable to Shareholders		110			108
	Accrued Expenses and Other Liabilities		81			91
	TOTAL LIABILITIES		3,491			3,774
	Shareholders’ Equity
	Preferred Stock — Authorized 8,000,000 Shares;		—			—
	$1 Par Value; Issued — None
	Common Stock — Authorized 1,200,000,000 Shares;		372			372
	$1 Par Value; Issued 371,980,460 Shares
	Paid-In Surplus		171			178
	Retained Earnings		21,902			20,009
	Accumulated Other Comprehensive Income		1,035			1,431
	Treasury Stock, at Cost — 123,673,969 and 110,217,445 Shares		(7,383	)		(6,163	)
	TOTAL SHAREHOLDERS’ EQUITY		16,097			15,827
	TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$	19,588		$	19,601
	The condensed financial statements should be read in conjunction with the consolidated financial statements and notes thereto.
	THE CHUBB CORPORATION
	Schedule II
	(continued)
	CONDENSED FINANCIAL INFORMATION OF REGISTRANT
	STATEMENTS OF INCOME — PARENT COMPANY ONLY
	(in millions)
	Years Ended December 31
		2013			2012			2011
	Revenues
	Investment Income	$	29		$	38		$	46
	Other Revenues		6			—			—
	Realized Investment Gains (Losses), Net		99			(6	)		9
	TOTAL REVENUES		134			32			55
	Expenses
	Corporate Expenses		262			268			285
	Investment Expenses		4			2			3
	Other Expenses		8			—			—
	TOTAL EXPENSES		274			270			288
	Loss before Federal and Foreign Income Tax and Equity in Net Income of Consolidated Subsidiaries		(140	)		(238	)		(233	)
	Federal and Foreign Income Tax		—			4			1
	Loss before Equity in Net Income of Consolidated Subsidiaries		(140	)		(242	)		(234	)
	Equity in Net Income of Consolidated Subsidiaries		2,485			1,787			1,912
	NET INCOME		2,345			1,545			1,678
	Other Comprehensive Income (Loss), Net of Tax		(396	)		236			405
	COMPREHENSIVE INCOME	$	1,949		$	1,781		$	2,083
	Chubb and its U.S. subsidiaries file a consolidated federal income tax return. The federal income tax provision represents an allocation under the Corporation’s tax allocation agreements.
	The condensed financial statements should be read in conjunction with the consolidated financial statements and notes thereto.
	THE CHUBB CORPORATION
	Schedule II
	(continued)
CONDENSED FINANCIAL INFORMATION OF REGISTRANT
STATEMENTS OF CASH FLOWS — PARENT COMPANY ONLY
(in millions)
Years Ended December 31
	2013			2012			2011
Cash Flows from Operating Activities
Net Income	$	2,345		$	1,545		$	1,678
Adjustments to Reconcile Net Income to Net Cash Used in Operating Activities
Equity in Net Income of Consolidated Subsidiaries		(2,485	)		(1,787	)		(1,912	)
Realized Investment Losses (Gains), Net		(99	)		6			(9	)
Other, Net		21			57			(28	)
NET CASH USED IN OPERATING ACTIVITIES		(218	)		(179	)		(271	)
Cash Flows from Investing Activities
Proceeds from Fixed Maturities
Sales		227			24			2
Maturities, Calls and Redemptions		150			673			456
Proceeds from Sales of Equity Securities		296			—			9
Purchases of Fixed Maturities		(198	)		(1,046	)		(257	)
Investments in Other Invested Assets, Net		22			—			—
Decrease (Increase) in Short Term Investments, Net		85			89			(219	)
Dividends Received from Consolidated Insurance Subsidiaries		1,564			1,760			2,700
Distributions Received from Consolidated Non-Insurance Subsidiaries		1			1			1
Other, Net		46			1			56
NET CASH PROVIDED BY INVESTING ACTIVITIES		2,193			1,502			2,748
Cash Flows from Financing Activities
Repayment of Long Term Debt		(275	)		—			(400	)
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans		38			74			80
Repurchase of Shares		(1,288	)		(959	)		(1,707	)
Dividends Paid to Shareholders		(450	)		(438	)		(450	)
NET CASH USED IN FINANCING ACTIVITIES		(1,975	)		(1,323	)		(2,477	)
Net Increase in Cash		—			—			—
Cash at Beginning of Year		—			—			—
CASH AT END OF YEAR	$	—		$	—		$	—
The condensed financial statements should be read in conjunction with the consolidated financial statements and notes thereto.
In 2013, Chubb exchanged its holdings of common stock and warrants of Alterra Capital Holdings Limited, with a cost basis of $177 million and a carrying value of $63 million, respectively, for common stock of Markel Corporation, valued at $226 million, and cash of $98 million, as a result of a business combination. The noncash portions of the transaction have been excluded from the statement of cash flows.

Consolidated_Supplementary_Ins

Consolidated Supplementary Insurance Information	12 Months Ended
	Dec. 31, 2013
Supplemental Information For Property Casualty Insurance Underwriters [Abstract]	'
Consolidated Supplementary Insurance Information	'
	THE CHUBB CORPORATION
	Schedule III
	CONSOLIDATED SUPPLEMENTARY INSURANCE INFORMATION
	(in millions)
			December 31						Year Ended December 31
	Segment		Deferred		Unpaid		Unearned		Premiums			Net		Insurance			Amortization		Other		Premiums
			Policy		Losses		Premiums		Earned			Investment		Losses			of Deferred		Insurance		Written
			Acquisition									Income (a)					Policy		Operating
			Costs														Acquisition		Costs and
																	Costs		Expenses (b)
	2013
	Property and Casualty Insurance
	Personal		$	505	$	2,235	$	2,216	$	4,214				$	2,224		$	982	$	465	$	4,322
	Commercial			493		13,147		2,792		5,237					2,891			970		665		5,273
	Specialty			257		7,307		1,412		2,618					1,417			502		287		2,633
	Reinsurance Assumed			—		457		3		(3	)				(12	)		—		—		(4	)
	Investments											$	1,391
			$	1,255	$	23,146	$	6,423	$	12,066		$	1,391	$	6,520		$	2,454	$	1,417	$	12,224
	2012
	Property and Casualty Insurance
	Personal		$	477	$	2,493	$	2,133	$	4,024				$	2,417		$	942	$	458	$	4,125
	Commercial			477		13,288		2,794		5,144					3,512			970		620		5,174
	Specialty			252		7,622		1,429		2,666					1,622			499		293		2,568
	Reinsurance Assumed			—		560		5		4					(44	)		—		1		3
	Investments											$	1,482
			$	1,206	$	23,963	$	6,361	$	11,838		$	1,482	$	7,507		$	2,411	$	1,372	$	11,870
	2011
	Property and Casualty Insurance
	Personal		$	466	$	2,241	$	2,048	$	3,917				$	2,508		$	900	$	436	$	3,977
	Commercial			475		12,422		2,746		4,945					3,366			929		617		5,051
	Specialty			269		7,677		1,519		2,769					1,558			501		278		2,720
	Reinsurance Assumed			—		728		9		13					(25	)		—		2		10
	Investments											$	1,562
			$	1,210	$	23,068	$	6,322	$	11,644		$	1,562	$	7,407		$	2,330	$	1,333	$	11,758
	(a)	Property and casualty assets are available for payment of losses and expenses for all classes of business; therefore, such assets and the related investment income have not been allocated to the underwriting segments.
	(b)	Other insurance operating costs and expenses does not include other income and charges.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Basis of Presentation	'
	(a)	Basis of Presentation
	The Chubb Corporation (Chubb) is a holding company with subsidiaries principally engaged in the property and casualty insurance business. The property and casualty insurance subsidiaries (the P&C Group) underwrite most lines of property and casualty insurance in the United States, Canada, Europe, Australia and parts of Latin America and Asia. The geographic distribution of property and casualty business in the United States is broad with a particularly strong market presence in the Northeast.
	The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include the accounts of Chubb and its subsidiaries (collectively, the Corporation). Significant intercompany transactions have been eliminated in consolidation. The results of our operations in Australia, Brazil and other smaller foreign locations are recorded on a three month lag in our consolidated financial statements. Specific events having significant financial impact that occur during the lag period are included in the current period results.
	The consolidated financial statements include amounts based on informed estimates and judgments of management for transactions that are not yet complete. Such estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Certain amounts in the consolidated financial statements for prior years have been reclassified to conform with the 2013 presentation.
Invested Assets	'
	(b)	Invested Assets
	Short term investments, which have an original maturity of one year or less, are carried at amortized cost, which approximates fair value.
	Fixed maturities, which include taxable and tax exempt bonds, are classified as available-for-sale and carried at fair value as of the balance sheet date. Taxable bonds include U.S. government and government agency and authority obligations, including taxable bonds issued by states, municipalities and political subdivisions within the United States, and foreign government and government agency obligations, corporate bonds and mortgage-backed securities. Corporate bonds include redeemable preferred stocks. Tax exempt bonds consist of bonds issued by states, municipalities and political subdivisions within the United States. Fixed maturities are purchased to support the investment strategies of the Corporation. These strategies are developed based on many factors including rate of return, maturity, credit risk, tax considerations and regulatory requirements. Fixed maturities may be sold prior to maturity to support the investment strategies of the Corporation.
	Premiums and discounts arising from the purchase of fixed maturities are amortized using the interest method over the estimated remaining term of the securities. For mortgage-backed securities, prepayment assumptions are reviewed periodically and revised as necessary.
	Equity securities, which include common stocks and non-redeemable preferred stocks, are carried at fair value as of the balance sheet date.
	Unrealized appreciation or depreciation, including unrealized other-than-temporary impairment losses, of fixed maturities and equity securities carried at fair value is excluded from net income and is included, net of applicable deferred income tax, in other comprehensive income.
	Other invested assets primarily include private equity limited partnerships which are carried at the Corporation’s equity in the net assets of the partnerships based on valuations provided by the manager of each partnership. As a result of the timing of the receipt of valuation data from the investment managers, these investments are generally reported on a three month lag. Changes in the Corporation’s equity in the net assets of the partnerships are included in net income as realized investment gains or losses. Other invested assets also include warrants, which are carried at fair value as of the balance sheet date. Changes in the fair value of warrants are included in net income as realized investment gains or losses.
	Realized gains and losses on the sale of investments are determined on the basis of the cost of the specific investments sold and are included in net income.
	When the fair value of an investment is lower than its cost, an assessment is made to determine whether the decline is temporary or other than temporary. The assessment of other-than-temporary impairment of fixed maturities and equity securities is based on both quantitative criteria and qualitative information. A number of factors are considered including, but not limited to, the length of time and the extent to which the fair value has been less than the cost, the financial condition and near term prospects of the issuer, whether the issuer is current on contractually obligated interest and principal payments, general market conditions and industry or sector specific factors.
	In determining whether fixed maturities are other than temporarily impaired, the Corporation is required to recognize an other-than-temporary impairment loss when it concludes it has the intent to sell or it is more likely than not it will be required to sell an impaired fixed maturity before the security recovers to its amortized cost value or it is likely it will not recover the entire amortized cost value of an impaired security. If the Corporation has the intent to sell or it is more likely than not that the Corporation will be required to sell an impaired fixed maturity before the security recovers to its amortized cost value, the security is written down to fair value and the entire amount of the writedown is included in net income as a realized investment loss. For all other impaired fixed maturities, when the impairment is determined to be other than temporary, the impairment loss is separated into the amount representing the credit loss and the amount representing the loss related to all other factors. The amount of the impairment loss that represents the credit loss is included in net income as a realized investment loss and the amount of the impairment loss that relates to all other factors is included in other comprehensive income.
	For fixed maturities, the split between the amount of other-than-temporary impairment losses that represents credit losses and the amount that relates to all other factors is principally based on assumptions regarding the amount and timing of projected cash flows. For fixed maturities other than mortgage-backed securities, cash flow estimates are based on assumptions regarding the probability of default and estimates regarding the timing and amount of recoveries associated with a default. For mortgage-backed securities, cash flow estimates are based on assumptions regarding future prepayment rates, default rates, loss severity and timing of recoveries. The Corporation has developed the estimates of projected cash flows using information based on historical market data, industry analyst reports and forecasts and other data relevant to the collectibility of a security.
	In determining whether equity securities are other than temporarily impaired, the Corporation considers its intent and ability to hold a security for a period of time sufficient to allow for the recovery of cost. If the decline in the fair value of an equity security is deemed to be other than temporary, the security is written down to fair value and the amount of the writedown is included in net income as a realized investment loss.
Premium Revenues and Related Expenses	'
	(c)	Premium Revenues and Related Expenses
	Insurance premiums are earned on a monthly pro rata basis over the terms of the policies and include estimates of audit premiums and premiums on retrospectively rated policies. Assumed reinsurance premiums are earned over the terms of the reinsurance contracts. Unearned premiums represent the portion of direct and assumed premiums written applicable to the unexpired terms of the insurance policies and reinsurance contracts in force.
	Ceded reinsurance premiums are reflected in operating results over the terms of the reinsurance contracts. Prepaid reinsurance premiums represent the portion of premiums ceded to reinsurers applicable to the unexpired terms of the reinsurance contracts in force.
	Reinsurance reinstatement premiums are recognized in the same period as the loss event that gave rise to the reinstatement premiums.
	Acquisition costs that are directly related to the successful acquisition of new or renewal insurance contracts are deferred and amortized over the period in which the related premiums are earned. Such costs include commissions, premium taxes and certain other underwriting and policy issuance costs. Commissions received related to reinsurance premiums ceded are considered in determining net acquisition costs eligible for deferral. Deferred policy acquisition costs are reviewed to determine whether they are recoverable from future income. If such costs are deemed to be unrecoverable, they are expensed. Anticipated investment income is considered in the determination of the recoverability of deferred policy acquisition costs.
Unpaid Losses and Loss Expenses	'
	(d)	Unpaid Losses and Loss Expenses
	Unpaid losses and loss expenses (also referred to as loss reserves) include the accumulation of individual case estimates for claims that have been reported and estimates of claims that have been incurred but not reported as well as estimates of the expenses associated with processing and settling all reported and unreported claims, less estimates of anticipated salvage and subrogation recoveries. Estimates are based upon past loss experience modified for current trends as well as prevailing economic, legal and social conditions. Loss reserves are not discounted to present value.
	Loss reserves are regularly reviewed using a variety of actuarial techniques. Reserve estimates are updated as historical loss experience develops, additional claims are reported and/or settled and new information becomes available. Any changes in estimates are reflected in operating results in the period in which the estimates are changed.
	Reinsurance recoverable on unpaid losses and loss expenses represents an estimate of the portion of gross loss reserves that will be recovered from reinsurers. Amounts recoverable from reinsurers are estimated using assumptions that are consistent with those used in estimating the gross losses associated with the reinsured policies. A provision for estimated uncollectible reinsurance is recorded based on periodic evaluations of balances due from reinsurers, the financial condition of the reinsurers, coverage disputes and other relevant factors.
Financial Products	'
	(e)	Financial Products
	Derivatives are carried at fair value as of the balance sheet date. Changes in fair value are recognized in net income in the period of the change and are included in other revenues.
	Assets and liabilities related to the derivatives are included in other assets and other liabilities.
Goodwill	'
	(f)	Goodwill
	Goodwill represents the excess of the cost of an acquired entity over the fair value of net assets acquired. Goodwill is tested for impairment at least annually.
Property and Equipment	'
	(g)	Property and Equipment
	Property and equipment used in operations, including certain costs incurred to develop or obtain computer software for internal use, are capitalized and carried at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. Property and equipment are included in other assets.
Real Estate	'
	(h)	Real Estate
	Real estate properties are carried at cost less accumulated depreciation and any writedowns for impairment. Real estate properties are reviewed for impairment whenever events or circumstances indicate that the carrying value of such properties may not be recoverable. Measurement of such impairment is based on the fair value of the property. Real estate properties are included in other assets.
Income Taxes	'
	(i)	Income Taxes
	Deferred income tax assets and liabilities are recognized for the expected future tax effects attributable to temporary differences between the financial reporting and tax bases of assets and liabilities, based on enacted tax rates and other provisions of tax law. The effect on deferred tax assets and liabilities of a change in tax laws or rates is recognized in net income in the period in which such change is enacted. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax assets will not be realized.
	The Corporation does not consider the earnings of its foreign subsidiaries to be permanently reinvested. Accordingly, provision has been made for the expected U.S. federal income tax liabilities applicable to undistributed earnings of foreign subsidiaries.
Stock-Based Employee Compensation	'
	(j)	Stock-Based Employee Compensation
	The fair value method of accounting is used for stock-based employee compensation plans. Under the fair value method, compensation cost is measured based on the fair value of the award at the grant date and recognized over the requisite service period.
Foreign Exchange	'
	(k)	Foreign Exchange
	Assets and liabilities relating to foreign operations are translated into U.S. dollars using current exchange rates as of the balance sheet date. Revenues and expenses are translated into U.S. dollars using the average exchange rates during the year.
	The functional currency of foreign operations is generally the currency of the local operating environment since business is primarily transacted in such local currency. Translation gains and losses, net of applicable income tax, are excluded from net income and are credited or charged directly to other comprehensive income.
Cash Flow Information	'
	(l)	Cash Flow Information
	In the statement of cash flows, short term investments are not considered to be cash equivalents. The effect of changes in foreign exchange rates on cash balances was insignificant.
	In 2013, the Corporation exchanged its holdings of common stock and warrants of Alterra Capital Holdings Limited, with a cost basis of $177 million and a carrying value of $63 million, respectively, for common stock of Markel Corporation, valued at $226 million, and cash of $98 million, as a result of a business combination. The noncash portions of the transaction have been excluded from the statement of cash flows.

Invested_Assets_and_Related_In1

Invested Assets and Related Income (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Amortized Cost and Fair Value of Fixed Maturities and Equity Securities	'
	(a)  The amortized cost and fair value of fixed maturities and equity securities were as follows:
		December 31, 2013
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Appreciation			Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	17,808		$	802		$	189		$	18,421
	Taxable
	U.S. government and government agency and		784			27			9			802
	authority obligations
	Corporate bonds		9,032			370			88			9,314
	Foreign government and government agency obligations		6,719			206			35			6,890
	Residential mortgage-backed securities		277			23			1			299
	Commercial mortgage-backed securities		1,339			29			3			1,365
			18,151			655			136			18,670
	Total fixed maturities	$	35,959		$	1,457		$	325		$	37,091
	Equity securities	$	1,057		$	756		$	3		$	1,810
		December 31, 2012
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Appreciation			Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	18,410		$	1,522		$	19		$	19,913
	Taxable
	U.S. government and government agency and authority obligations		973			66			—			1,039
	Corporate bonds		7,331			609			3			7,937
	Foreign government and government agency obligations		6,614			395			1			7,008
	Residential mortgage-backed securities		421			36			2			455
	Commercial mortgage-backed securities		1,649			76			1			1,724
			16,988			1,182			7			18,163
	Total fixed maturities	$	35,398		$	2,704		$	26		$	38,076
	Equity securities	$	1,244		$	453		$	34		$	1,663
Summary of Fair Value of Tax Exempt Fixed Maturities	'
	The following table summarizes the fair value of the tax exempt fixed maturities at December 31, 2013 and 2012:
		2013			2012
		(in millions)
	Special revenue bonds	$	11,717		$	12,233
	State general obligation bonds		2,292			2,246
	Municipal and political subdivision general obligation bonds		2,220			2,505
	Pre-refunded bonds		2,192			2,929
		$	18,421		$	19,913
Fair Value and Amortized Cost of Tax Exempt Fixed Maturities Other Than Pre-Refunded Bonds	'
	The following table summarizes the fair value and amortized cost of the tax exempt fixed maturities other than pre-refunded bonds held at December 31, 2013 and 2012, for the five states having the largest concentration of issuers within the tax exempt fixed maturity portfolio. The remainder of tax exempt fixed maturities were issued by a broad range of other states and municipalities and political subdivisions within those states. In the following table, “state” identifies the issuer or the location of the issuing municipality or political subdivision within a state.
		December 31, 2013
		Fair Value
	State	Special			Municipal			State			Total		Amortized
		Revenue			and  Political			General					Cost
		Bonds			Subdivision			Obligations
					General
					Obligations
		(in millions)
	Texas	$	930		$	830		$	230		$	1,990	$	1,904
	New York		1,611			197			31			1,839		1,809
	California		859			82			198			1,139		1,093
	Illinois		577			483			56			1,116		1,094
	Florida		757			38			108			903		877
		December 31, 2012
		Fair Value
	State	Special			Municipal			State			Total		Amortized
		Revenue			and Political			General					Cost
		Bonds			Subdivision			Obligations
					General
					Obligations
		(in millions)
	Texas	$	1,041		$	1,053		$	267		$	2,361	$	2,171
	New York		1,401			169			33			1,603		1,487
	Illinois		683			518			59			1,260		1,161
	California		888			107			194			1,189		1,089
	Florida		771			27			114			912		844
Fair Value and Amortized Cost of Foreign Government and Government Agency Fixed Maturities	'
	The following table summarizes the fair value and amortized cost of the foreign government and government agency fixed maturities held at December 31, 2013 and 2012, for the five countries having the largest concentration of issuers within the foreign government and government agency fixed maturity portfolio. In the following table, “country” identifies the issuer or the location of the issuing government agency or regional government within a country.
		2013						2012
	Country	Fair			Amortized			Fair			Amortized
		Value			Cost			Value			Cost
		(in millions)
	Canada	$	1,993		$	1,953		$	2,157		$	2,060
	Germany		1,241			1,211			1,127			1,070
	United Kingdom		1,026			1,004			1,024			939
	Australia		739			700			742			663
	Brazil		270			270			310			310
Fair Value and Amortized Cost of Fixed Maturities by Contractual Maturity	'
	The fair value and amortized cost of fixed maturities at December 31, 2013 by contractual maturity were as follows:
		Fair			Amortized
		Value			Cost
		(in millions)
	Due in one year or less	$	2,241		$	2,212
	Due after one year through five years		13,769			13,202
	Due after five years through ten years		11,743			11,294
	Due after ten years		7,674			7,635
			35,427			34,343
	Residential mortgage-backed securities		299			277
	Commercial mortgage-backed securities		1,365			1,339
		$	37,091		$	35,959
Components of Unrealized Appreciation or Depreciation of Investments	'
	(b)  The components of unrealized appreciation or depreciation, including unrealized other-than-temporary impairment losses, of investments carried at fair value were as follows:
		December 31
		2013			2012
		(in millions)
	Fixed maturities
	Gross unrealized appreciation	$	1,457		$	2,704
	Gross unrealized depreciation		325			26
			1,132			2,678
	Equity securities
	Gross unrealized appreciation		756			453
	Gross unrealized depreciation		3			34
			753			419
			1,885			3,097
	Deferred income tax liability		660			1,084
		$	1,225		$	2,013
Fair Value and Gross Unrealized Depreciation of Investments in Unrealized Loss Position	'
	The following table summarizes, for all investment securities in an unrealized loss position at December 31, 2013, the aggregate fair value and gross unrealized depreciation, including unrealized other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position.
		Less Than 12 Months						12 Months or More					Total
		Fair			Gross			Fair			Gross		Fair		Gross
		Value			Unrealized			Value			Unrealized		Value		Unrealized
					Depreciation						Depreciation				Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	3,417		$	144		$	307		$	45	$	3,724	$	189
	Taxable
	U.S. government and government agency		213			6			35			3		248		9
	and authority obligations
	Corporate bonds		2,526			76			222			12		2,748		88
	Foreign government and government		1,735			32			75			3		1,810		35
	agency obligations
	Residential mortgage-backed securities		4			—			14			1		18		1
	Commercial mortgage-backed securities		153			1			39			2		192		3
			4,631			115			385			21		5,016		136
	Total fixed maturities		8,048			259			692			66		8,740		325
	Equity securities		41			3			—			—		41		3
		$	8,089		$	262		$	692		$	66	$	8,781	$	328
	At December 31, 2013, approximately 1,160 individual fixed maturities and 10 individual equity securities were in an unrealized loss position. The Corporation does not have the intent to sell and it is not more likely than not that the Corporation will be required to sell these fixed maturities before the securities recover to their amortized cost value. In addition, the Corporation believes that none of the declines in the fair values of these fixed maturities relate to credit losses. The Corporation has the intent and ability to hold the equity securities in an unrealized loss position for a period of time sufficient to allow for the recovery of cost. The Corporation believes that none of the declines in the fair value of these fixed maturities and equity securities were other than temporary at December 31, 2013.
	The following table summarizes, for all investment securities in an unrealized loss position at December 31, 2012, the aggregate fair value and gross unrealized depreciation, including unrealized other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position.
		Less Than 12 Months						12 Months or More					Total
		Fair			Gross			Fair			Gross		Fair		Gross
		Value			Unrealized			Value			Unrealized		Value		Unrealized
					Depreciation						Depreciation				Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	344		$	6		$	104		$	13	$	448	$	19
	Taxable
	U.S. government and government agency and authority obligations		28			—			20			—		48		—
	Corporate bonds		289			2			14			1		303		3
	Foreign government and government agency obligations		429			1			13			—		442		1
	Residential mortgage-backed securities		1			—			19			2		20		2
	Commercial mortgage-backed securities		105			1			3			—		108		1
			852			4			69			3		921		7
	Total fixed maturities		1,196			10			173			16		1,369		26
	Equity securities		182			21			63			13		245		34
		$	1,378		$	31		$	236		$	29	$	1,614	$	60
Change in Unrealized Appreciation or Depreciation of Investments Carried at Fair Value	'
	The change in unrealized appreciation or depreciation of investments carried at fair value, including the change in unrealized other-than-temporary impairment losses, was as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Change in unrealized appreciation of fixed maturities	$	(1,546	)	$	256		$	964
	Change in unrealized appreciation of equity securities		334			171			(17	)
			(1,212	)		427			947
	Deferred income tax (credit)		(424	)		150			331
		$	(788	)	$	277		$	616
Sources of Net Investment Income	'
	(c)  The sources of net investment income were as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Fixed maturities	$	1,380		$	1,465		$	1,549
	Equity securities		38			40			34
	Short term investments		16			18			16
	Other		31			33			45
	Gross investment income		1,465			1,556			1,644
	Investment expenses		49			38			39
		$	1,416		$	1,518		$	1,605
Realized Investment Gains and Losses	'
	(d)  Realized investment gains and losses were as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Fixed maturities
	Gross realized gains	$	62		$	124		$	70
	Gross realized losses		(42	)		(20	)		(39	)
	Other-than-temporary impairment losses		(2	)		(5	)		(1	)
			18			99			30
	Equity securities
	Gross realized gains		204			68			74
	Gross realized losses		(1	)		—			(1	)
	Other-than-temporary impairment losses		(9	)		(40	)		(22	)
			194			28			51
	Other invested assets		190			66			207
		$	402		$	193		$	288

Deferred_Policy_Acquisition_Co1

Deferred Policy Acquisition Costs (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Policy Acquisition Costs Deferred and Related Amortization Reflected in Operating Results	'
	Policy acquisition costs deferred and the related amortization reflected in operating results were as follows:
		Years Ended December 31
		2013			2012			2011
					(in millions)
	Balance, beginning of year	$	1,206		$	1,210		$	1,142
	Costs deferred during year
	Commissions and brokerage		1,979			1,919			1,910
	Premium taxes and assessments		263			247			235
	Underwriting and policy issuance costs		271			248			248
			2,513			2,414			2,393
	Foreign currency translation effect		(10	)		(7	)		5
	Amortization during year		(2,454	)		(2,411	)		(2,330	)
	Balance, end of year	$	1,255		$	1,206		$	1,210

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Schedule of Property and Equipment	'
	Property and equipment included in other assets were as follows:
		December 31
		2013		2012
		(in millions)
	Cost	$	501	$	517
	Accumulated depreciation		243		248
		$	258	$	269

Unpaid_Losses_and_Loss_Expense1

Unpaid Losses and Loss Expenses (Tables)	12 Months Ended
	Dec. 31, 2013
Insurance [Abstract]	'
Reconciliation of Beginning and Ending Liability for Unpaid Losses and Loss Expenses	'
	A reconciliation of the beginning and ending liability for unpaid losses and loss expenses, net of reinsurance recoverable, and a reconciliation of the net liability to the corresponding liability on a gross basis is as follows:
		2013			2012			2011
		(in millions)
	Gross liability, beginning of year	$	23,963		$	23,068		$	22,718
	Reinsurance recoverable, beginning of year		1,941			1,739			1,817
	Net liability, beginning of year		22,022			21,329			20,901
	Net incurred losses and loss expenses related to
	Current year		7,232			8,121			8,174
	Prior years		(712	)		(614	)		(767	)
			6,520			7,507			7,407
	Net payments for losses and loss expenses related to
	Current year		2,150			2,323			2,746
	Prior years		4,952			4,493			4,300
			7,102			6,816			7,046
	Foreign currency translation effect		(96	)		2			67
	Net liability, end of year		21,344			22,022			21,329
	Reinsurance recoverable, end of year		1,802			1,941			1,739
	Gross liability, end of year	$	23,146		$	23,963		$	23,068

Debt_and_Credit_Arrangements_T

Debt and Credit Arrangements (Tables)	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Long Term Debt	'
	(a)   Long term debt consisted of the following:
		December 31
		2013		2012
		(in millions)
	5.2% notes due April 1, 2013	$	—	$	275
	5.75% notes due May 15, 2018		600		600
	6.6% debentures due August 15, 2018		100		100
	6.8% debentures due November 15, 2031		200		200
	6% notes due May 11, 2037		800		800
	6.5% notes due May 15, 2038		600		600
	6.375% capital securities due March 29, 2067		1,000		1,000
		$	3,300	$	3,575
Amounts of Long Term Debt due Annually	'
	The amounts of long term debt due annually during the five years subsequent to December 31, 2013 are as follows:
	Years Ending December 31	(in millions)
	2014	$	—
	2015		—
	2016		—
	2017		—
	2018		700

Federal_and_Foreign_Income_Tax1

Federal and Foreign Income Tax (Tables)	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Tax Expense and Taxes Paid	'
	Income tax expense and taxes paid consisted of the following components:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Income tax expense
	Current tax
	United States	$	791		$	276		$	260
	Foreign		91			143			236
	Deferred tax, principally United States		10			32			25
		$	892		$	451		$	521
	Federal and foreign income taxes paid	$	789		$	472		$	598
Reconciliation of Effective Income Tax Rate and Statutory Federal Corporate Tax Rate	'
	The effective income tax rate is different than the statutory federal corporate tax rate. The reasons for the different effective tax rate were as follows:
		Years Ended December 31
		2013						2012						2011
		Amount			% of			Amount			% of			Amount			% of
					Pre-Tax						Pre-Tax						Pre-Tax
					Income						Income						Income
		(in millions)
	Income before federal and foreign income tax	$	3,237					$	1,996					$	2,199
	Tax at statutory federal income tax rate	$	1,133			35	%	$	699			35	%	$	770			35	%
	Tax exempt interest income		(222	)		(6.8	)		(233	)		(11.7	)		(243	)		(11.0	)
	Other, net		(19	)		(.6	)		(15	)		(.7	)		(6	)		(.3	)
	Federal and foreign income tax	$	892			27.6	%	$	451			22.6	%	$	521			23.7	%
Tax Effects of Temporary Differences that Gave Rise to Deferred Income Tax Assets and Liabilities	'
	The tax effects of temporary differences that gave rise to deferred income tax assets and liabilities were as follows:
		December 31
		2013			2012
		(in millions)
	Deferred income tax assets
	Unpaid losses and loss expenses	$	524		$	605
	Unearned premiums		350			341
	Foreign tax credits		867			870
	Employee compensation		142			119
	Postretirement benefits		95			324
	Other-than-temporary impairment losses		291			294
	Total		2,269			2,553
	Deferred income tax liabilities
	Deferred policy acquisition costs		356			341
	Unremitted earnings of foreign subsidiaries		970			951
	Unrealized appreciation of investments		660			1,084
	Other invested assets		184			225
	Other, net		52			114
	Total		2,222			2,715
	Net deferred income tax asset (liability)	$	47		$	(162	)

Reinsurance_Tables

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2013
Insurance [Abstract]	'
Effect of Reinsurance on Premiums Written and Earned	'
	The effect of reinsurance on the premiums written and earned of the P&C Group was as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Direct premiums written	$	12,804		$	12,647		$	12,452
	Assumed reinsurance		503			423			398
	Ceded reinsurance		(1,083	)		(1,200	)		(1,092	)
	Net premiums written	$	12,224		$	11,870		$	11,758
	Direct premiums earned	$	12,717		$	12,596		$	12,387
	Assumed reinsurance		476			422			365
	Ceded reinsurance		(1,127	)		(1,180	)		(1,108	)
	Net premiums earned	$	12,066		$	11,838		$	11,644

StockBased_Employee_Compensati1

Stock-Based Employee Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Additional Information With Respect to Restricted Stock Units and Performance Units	'
	Additional information with respect to restricted stock units and performance units is as follows:
			Restricted Stock Units					Performance Units*
			Number			Weighted Average		Number			Weighted Average
			of Shares			Grant Date		of Shares			Grant Date
						Fair Value					Fair Value
	Nonvested, January 1, 2013			2,418,946		$	59.54		973,909		$	63.88
	Granted			668,754			83.75		408,989			98.46
	Vested**			(852,786	)		51.42		(500,409	)		64.34
	Forfeited			(107,267	)		63		(21,348	)		70.58
	Nonvested, December 31, 2013			2,127,647			70.23		861,141			79.87
		*	The number of shares earned may range from 0% to 200% of the performance units shown in the table above.
		**	The performance units earned in 2013 were 132.6% of the vested shares shown in the table, or 663,542 shares.
Stock Option Pricing Weighted Average Assumptions	'
	The fair value of each stock option was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions:
			2013			2012		2011
	Risk-free interest rate			0.90%			1.00%		2.40%
	Expected volatility			24.40%			24.60%		24.20%
	Dividend yield			2.10%			2.40%		2.60%
	Expected average term (in years)			5.5			5.5		5.5
Additional Information with Respect to Stock Options	'
	Additional information with respect to stock options is as follows:
			Number			Weighted		Weighted Average			Aggregate
			of Shares			Average		Remaining			Intrinsic Value
						Exercise Price		Contractual Term
								(in years)			(in millions)
	Outstanding, January 1, 2013			520,575		$	40.24
	Granted			71,903			83.89
	Exercised			(317,256	)		32.48
	Forfeited			(23,535	)		39.94
	Outstanding, December 31, 2013			251,687			62.52		6.6		$	9
	Exercisable, December 31, 2013			127,475			48.93		4.7			6

Employee_Benefits_Tables

Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 2013
Compensation And Retirement Disclosure [Abstract]	'
Funded Status of Pension and Other Postretirement Benefit Plans	'
	The funded status of the pension and other postretirement benefit plans at December 31, 2013 and 2012 was as follows:
		Pension						Other
		Benefits						Postretirement
								Benefits
		2013			2012			2013			2012
		(in millions)
	Benefit obligation, beginning of year	$	2,894		$	2,494		$	470		$	454
	Service cost		95			88			13			12
	Interest cost		125			124			19			20
	Actuarial loss (gain)		(261	)		256			(97	)		(4	)
	Benefits paid		(75	)		(74	)		(11	)		(12	)
	Foreign currency translation effect		(1	)		6			—			—
	Benefit obligation, end of year		2,777			2,894			394			470
	Plan assets at fair value		2,717			2,305			130			96
	Funded status at end of year, included in other liabilities	$	60		$	589		$	264		$	374
Net Actuarial Loss (Gain) and Prior Service Cost Included in Accumulated Other Comprehensive Income	'
	Net actuarial loss (gain) and prior service cost included in accumulated other comprehensive income that were not yet recognized as components of net benefit costs at December 31, 2013 and 2012 were as follows:
		Pension						Other
		Benefits						Postretirement
								Benefits
		2013			2012			2013			2012
		(in millions)
	Net actuarial loss (gain)	$	396		$	989		$	(13	)	$	108
	Prior service cost		16			18			1			—
		$	412		$	1,007		$	(12	)	$	108
Weighted Average Assumptions Used to Determine Benefit Obligations	'
	The weighted average assumptions used to determine the benefit obligations were as follows:
		Pension Benefits						Other
								Postretirement
								Benefits
		2013			2012			2013			2012
	Discount rate		5.2	%		4.4	%		5.2	%		4.4	%
	Rate of compensation increase		4.5			4.5			—			—
Components of Net Pension and Other Postretirement Benefit Costs Reflected in Net Income	'
	The components of net pension and other postretirement benefit costs reflected in net income and other changes in plan assets for the years ended December 31, 2013, 2012 and 2011 were as follows:
		Pension Benefits									Other
											Postretirement Benefits
		2013			2012			2011			2013			2012			2011
		(in millions)
	Costs reflected in net income
	Service cost	$	95		$	88		$	79		$	13		$	12		$	11
	Interest cost		125			124			120			19			20			22
	Expected return on plan assets		(165	)		(155	)		(140	)		(7	)		(6	)		(5	)
	Amortization of net actuarial loss and prior service cost and other		90			80			68			3			3			3
		$	145		$	137		$	127		$	28		$	29		$	31
Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income	'
	The components of net pension and other postretirement benefit obligations recognized in other comprehensive income for the years ended December 31, 2013, 2012 and 2011 were as follows:
		Pension Benefits									Other
											Postretirement Benefits
		2013			2012			2011			2013			2012			2011
		(in millions)
	Costs reflected in net income
	Service cost	$	95		$	88		$	79		$	13		$	12		$	11
	Interest cost		125			124			120			19			20			22
	Expected return on plan assets		(165	)		(155	)		(140	)		(7	)		(6	)		(5	)
	Amortization of net actuarial loss and prior service cost and other		90			80			68			3			3			3
		$	145		$	137		$	127		$	28		$	29		$	31
	Changes in plan assets and benefit obligations recognized in other comprehensive income
	Net actuarial loss (gain)	$	(505	)	$	139		$	355		$	(117	)	$	(11	)	$	45
	Amortization of net actuarial loss and prior service cost and other		(90	)		(80	)		(68	)		(3	)		(3	)		(3	)
		$	(595	)	$	59		$	287		$	(120	)	$	(14	)	$	42
Weighted Average Assumptions Used to Determine Net Pension and Other Postretirement Benefit Costs	'
	The weighted average assumptions used to determine net pension and other postretirement benefit costs were as follows:
		Pension Benefits									Other
											Postretirement Benefits
		2013			2012			2011			2013			2012			2011
	Discount rate		4.40%			5.00%			5.75%			4.40%			5.00%			5.75%
	Rate of compensation increase		4.5			4.5			4.5			—			—			—
	Expected long term rate of return on plan assets		7.5			7.75			7.75			7.5			7.75			7.75
Weighted Average Health Care Cost Trend Rate Assumptions	'
	The weighted average health care cost trend rate assumptions used to measure the expected cost of medical benefits were as follows:
		December 31
		2013			2012
	Health care cost trend rate for next year		7.6	%		7.9	%
	Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		4.5			4.5
	Year that the rate reaches the ultimate trend rate		2028			2028
Fair Values of Pension Plan Assets	'
	The fair values of the pension plan assets were as follows:
		December 31
		2013			2012
		(in millions)
	Short term investments	$	37		$	33
	Fixed maturities
	U.S. government and government agency and authority obligations		224			239
	Corporate bonds		371			321
	Foreign government and government agency obligations		104			80
	Mortgage-backed securities		217			174
	Total fixed maturities		916			814
	Equity securities		1,718			1,404
	Other assets		46			54
		$	2,717		$	2,305
Estimated Benefits Expected to be Paid	'
	The estimated benefits expected to be paid in each of the next five years and in the aggregate for the following five years are as follows:
	Years Ending December 31	Pension			Other
		Benefits			Postretirement
					Benefits
		(in millions)
	2014	$	99		$	12
	2015		104			13
	2016		114			15
	2017		149			16
	2018		130			18
	2019-2023		803			114

Comprehensive_Income_Tables

Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Components of Other Comprehensive Income or Loss	'
	The components of other comprehensive income or loss were as follows:
			Years Ended December 31
			2013									2012									2011
			Before			Income			Net of			Before			Income			Net of			Before			Income			Net of
			Tax			Tax			Tax			Tax			Tax			Tax			Tax			Tax			Tax
												(in millions)
	Net unrealized holding gains (losses) arising		$	(1,000	)	$	(350	)	$	(650	)	$	556		$	195		$	361		$	1,029		$	359		$	670
	during the year
	Unrealized other-than-temporary			—			—			—			(2	)		(1	)		(1	)		(1	)		—			(1	)
	impairment losses arising during the year
	Reclassification adjustment for net realized			212			74			138			127			44			83			81			28			53
	gains included in net income
	Net unrealized gains (losses) recognized in other comprehensive income or loss			(1,212	)		(424	)		(788	)		427			150			277			947			331			616
	Postretirement benefit gain (loss) not yet			622			218			404			(128	)		(45	)		(83	)		(400	)		(140	)		(260	)
	recognized in net income arising during the year
	Reclassification adjustment for the			(93	)		(33	)		(60	)		(83	)		(30	)		(53	)		(71	)		(26	)		(45	)
	amortization of net actuarial loss and prior service cost included in net income (a)
	Net change in postretirement benefit			715			251			464			(45	)		(15	)		(30	)		(329	)		(114	)		(215	)
	costs not yet recognized in net income
	Foreign currency translation gains (losses)			(111	)		(39	)		(72	)		(16	)		(5	)		(11	)		6			2			4
	Total other comprehensive income (loss)		$	(608	)	$	(212	)	$	(396	)	$	366		$	130		$	236		$	624		$	219		$	405
	(a)	Postretirement benefit costs recognized in net income during the period are included among several of the loss and expense components presented in the consolidated statements of income.

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Rent Expense	'
	Rent expense was as follows:
		Years Ended
		December 31
		2013		2012		2011
		(in millions)
	Office facilities	$	71	$	71	$	73
	Equipment		13		11		10
		$	84	$	82	$	83
Future Minimum Rental Payments Required Under Non-Cancellable Operating Leases	'
	At December 31, 2013, future minimum rental payments required under non-cancellable operating leases were as follows:
	Years Ending December 31	(in millions)
	2014	$	67
	2015		59
	2016		47
	2017		37
	2018		32
	After 2018		74
		$	316

Segments_Information_Tables

Segments Information (Tables)	12 Months Ended
	Dec. 31, 2013
Segment Reporting [Abstract]	'
Revenues, Income Before Income Tax and Assets of Each Operating Segment	'
	Revenues, income before income tax and assets of each operating segment were as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Revenues
	Property and casualty insurance
	Premiums earned
	Personal insurance	$	4,214		$	4,024		$	3,917
	Commercial insurance		5,237			5,144			4,945
	Specialty insurance		2,618			2,666			2,769
	Total insurance		12,069			11,834			11,631
	Reinsurance assumed		(3	)		4			13
			12,066			11,838			11,644
	Investment income		1,436			1,518			1,598
	Total property and casualty insurance		13,502			13,356			13,242
	Corporate and other		43			46			55
	Realized investment gains, net		402			193			288
	Total revenues	$	13,947		$	13,595		$	13,585
	Income (loss) before income tax
	Property and casualty insurance
	Underwriting
	Personal insurance	$	509		$	192		$	47
	Commercial insurance		692			44			1
	Specialty insurance		406			262			427
	Total insurance		1,607			498			475
	Reinsurance assumed		9			47			36
			1,616			545			511
	Increase in deferred policy acquisition costs		59			3			63
	Underwriting income		1,675			548			574
	Investment income		1,391			1,482			1,562
	Other income		6			10			21
	Total property and casualty insurance		3,072			2,040			2,157
	Corporate and other		(237	)		(237	)		(246	)
	Realized investment gains, net		402			193			288
	Total income before income tax	$	3,237		$	1,996		$	2,199
		December 31
		2013			2012			2011
		(in millions)
	Assets
	Property and casualty insurance	$	48,278		$	49,441		$	48,017
	Corporate and other		2,248			2,830			2,513
	Adjustments and eliminations		(93	)		(87	)		(85	)
	Total assets	$	50,433		$	52,184		$	50,445
Revenues of Property and Casualty Group by Geographic Area	'
	Revenues of the P&C Group by geographic area were as follows:
		Years Ended December 31
		2013			2012			2011
		(in millions)
	Revenues
	United States	$	10,205		$	9,996		$	9,831
	International		3,297
						3,360			3,411
	Total	$	13,502		$	13,356		$	13,242

Fair_Values_of_Financial_Instr1

Fair Values of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
Carrying Values and Fair Values of Financial Instruments	'
	The carrying values and fair values of financial instruments were as follows:
		December 31
		2013				2012
		Carrying		Fair		Carrying		Fair
		Value		Value		Value		Value
		(in millions)
	Assets
	Invested assets
	Short term investments	$	2,114	$	2,114	$	2,528	$	2,528
	Fixed maturities (Note 2)		37,091		37,091		38,076		38,076
	Equity securities		1,810		1,810		1,663		1,663
	Other invested assets		—		—		46		46
	Liabilities
	Long term debt (Note 6)		3,300		3,806		3,575		4,372
Fair Value of Financial Instruments Categorized Based Upon Lowest Level of Input	'
	The fair value of financial instruments categorized based upon the lowest level of input that was significant to the fair value measurement was as follows:
		December 31, 2013
		Level 1		Level 2		Level 3		Total
		(in millions)
	Assets
	Short term investments	$	399	$	1,715	$	—	$	2,114
	Fixed maturities
	Tax exempt		—		18,416		5		18,421
	Taxable
	U.S. government and government agency and authority obligations		—		802		—		802
	Corporate bonds		—		9,179		135		9,314
	Foreign government and government agency obligations		—		6,881		9		6,890
	Residential mortgage-backed securities		—		293		6		299
	Commercial mortgage-backed securities		—		1,345		20		1,365
			—		18,500		170		18,670
	Total fixed maturities		—		36,916		175		37,091
	Equity securities		1,803		—		7		1,810
		$	2,202	$	38,631	$	182	$	41,015
	Liabilities
	Long term debt	$	—	$	3,806	$	—	$	3,806
		December 31, 2012
		Level 1		Level 2		Level 3		Total
		(in millions)
	Assets
	Short term investments	$	182	$	2,346	$	—	$	2,528
	Fixed maturities
	Tax exempt		—		19,907		6		19,913
	Taxable
	U.S. government and government agency and authority obligations		—		1,039		—		1,039
	Corporate bonds		—		7,779		158		7,937
	Foreign government and government agency obligations		—		7,008		—		7,008
	Residential mortgage-backed securities		—		446		9		455
	Commercial mortgage-backed securities		—		1,724		—		1,724
			—		17,996		167		18,163
	Total fixed maturities		—		37,903		173		38,076
	Equity securities		1,655		—		8		1,663
	Other invested assets		—		—		46		46
		$	1,837	$	40,249	$	227	$	42,313
	Liabilities
	Long term debt	$	—	$	4,372	$	—	$	4,372
Fair Values of Pension Plan Assets Categorized Based Upon Lowest Level of Input	'
	Based on the fair value hierarchy, the fair value of the Corporation’s pension plan assets categorized based upon the lowest level of input that was significant to the fair value measurement was as follows:
		December 31, 2013
		Level 1		Level 2		Level 3		Total
		(in millions)
	Short term investments	$	—	$	37	$	—	$	37
	Fixed maturities
	U.S. government and government agency and authority obligations		—		224		—		224
	Corporate bonds		—		370		1		371
	Foreign government and government agency obligations		—		104		—		104
	Mortgage-backed securities		—		211		6		217
	Total fixed maturities		—		909		7		916
	Equity securities		573		1,145		—		1,718
	Other assets		21		14		11		46
		$	594	$	2,105	$	18	$	2,717
		December 31, 2012
		Level 1		Level 2		Level 3		Total
		(in millions)
	Short term investments	$	—	$	33	$	—	$	33
	Fixed maturities
	U.S. government and government agency and authority obligations		—		238		1		239
	Corporate bonds		—		321		—		321
	Foreign government and government agency obligations		—		79		1		80
	Mortgage-backed securities		—		174		—		174
	Total fixed maturities		—		812		2		814
	Equity securities		457		947		—		1,404
	Other assets		29		9		16		54
		$	486	$	1,801	$	18	$	2,305

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Computation of Basic and Diluted Earnings Per Share	'
	The following table sets forth the computation of basic and diluted earnings per share:
		Years Ended December 31
		2013		2012		2011
		(in millions except for per
		share amounts)
	Basic earnings per share:
	Net income	$	2,345	$	1,545	$	1,678
	Weighted average shares outstanding		258.2		269.5		289.3
	Basic earnings per share	$	9.08	$	5.73	$	5.8
	Diluted earnings per share:
	Net income	$	2,345	$	1,545	$	1,678
	Weighted average shares outstanding		258.2		269.5		289.3
	Additional shares from assumed issuance of shares under stock-based compensation awards		1.2		1.9		2.1
	Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share		259.4		271.4		291.4
	Diluted earnings per share	$	9.04	$	5.69	$	5.76

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Common Stock Activity	'
	The activity of Chubb’s common stock was as follows:
		Years Ended December 31
		2013			2012			2011
		(number of shares)
	Common stock issued
	Balance, beginning and end of year		371,980,460			371,980,460			371,980,460
	Treasury stock
	Balance, beginning of year		110,217,445			99,519,509			74,707,547
	Repurchase of shares		14,887,701			13,094,640			27,582,889
	Share activity under stock-based employee compensation plans		(1,431,177	)		(2,396,704	)		(2,770,927	)
	Balance, end of year		123,673,969			110,217,445			99,519,509
	Common stock outstanding, end of year		248,306,491			261,763,015			272,460,951
Comparison of Shareholders' Equity on GAAP Basis and Policyholders' Surplus on Statutory Basis	'
	A comparison of shareholders’ equity on a GAAP basis and policyholders’ surplus on a statutory basis is as follows:
		December 31
		2013						2012
		GAAP			Statutory			GAAP			Statutory
		(in millions)
	P&C Group	$	17,398		$	15,024		$	16,833		$	14,117
	Corporate and other		(1,301	)					(1,006	)
		$	16,097					$	15,827
Comparison of GAAP and Statutory Net Income (Loss)	'
	A comparison of GAAP and statutory net income (loss) is as follows:
		Years Ended December 31
		2013						2012					2011
		GAAP			Statutory			GAAP			Statutory		GAAP			Statutory
		(in millions)
	P&C Group	$	2,480		$	2,485		$	1,791		$	1,936	$	1,915		$	1,824
	Corporate and other		(135	)					(246	)				(237	)
		$	2,345					$	1,545				$	1,678

Quarterly_Financial_Data_Table

Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Summary of Quarterly Financial Data	'
	Summarized unaudited quarterly financial data for 2013 and 2012 are shown below. In management’s opinion, the interim financial data contain all adjustments, consisting of normal recurring items, necessary to present fairly the results of operations for the interim periods.
			Three Months Ended
			March 31						June 30						September 30						December 31
			2013			2012			2013			2012			2013			2012			2013			2012(a)
			(in millions except for per share amounts)
	Revenues		$	3,517		$	3,410		$	3,551		$	3,423		$	3,403		$	3,362		$	3,476		$	3,400
	Losses and expenses			2,601			2,731			2,755			2,896			2,664			2,635			2,690			3,337
	Federal and foreign income			260			173			217			123			198			194			217			(39	)
	tax (credit)
	Net income		$	656		$	506		$	579		$	404		$	541		$	533		$	569		$	102
	Basic earnings per share		$	2.49		$	1.85		$	2.22		$	1.49		$	2.11		$	1.99		$	2.25		$	0.39
	Diluted earnings per share		$	2.48		$	1.83		$	2.21		$	1.48		$	2.1		$	1.98		$	2.24		$	0.38
	Underwriting ratios
	Losses to premiums earned			52.3	%		58	%		56.7	%		62.5	%		53	%		53.8	%		54.7	%		80.3	%
	Expenses to premiums written			32.3			32.2			32.1			31.3			32.7			32.5			30.8			30.9
	Combined			84.6	%		90.2	%		88.8	%		93.8	%		85.7	%		86.3	%		85.5	%		111.2	%
	(a)	In the fourth quarter of 2012, revenues were reduced by reinsurance reinstatement premium costs of $53 million and losses and expenses included net losses of $829 million related to Storm Sandy. Net income for the quarter was reduced by $573 million, or $2.15 of diluted earnings per share ($2.16 of basic earnings per share), for the after–tax effect of the net costs. Excluding the impact of Storm Sandy, the losses to premiums earned ratio was 50.9%, the expenses to premiums written ratio was 30.4% and the combined ratio was 81.3%.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
In Millions, unless otherwise specified					Alterra Common Stock [Member]	Alterra Warrants [Member]	Markel Corporation [Member]
Conversion of Stock [Line Items]	'	'	'	'	'	'	'
Holdings of common stock and warrants, cost basis	'	'	'	'	$177	$63	'
Transferred, common stock value	'	'	'	'	'	'	226
Cash	$52	$50	$58	$70	'	'	$98

Invested_Assets_and_Related_In2

Invested Assets and Related Income - Amortized Cost and Fair Value of Fixed Maturities and Equity Securities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Investment Holdings [Line Items]	'	'
Tax exempt, Amortized Cost	$17,808	$18,410
Taxable, Amortized Cost	18,151	16,988
Total fixed maturities, Amortized Cost	35,959	35,398
Equity securities, Amortized Cost	1,057	1,244
Tax exempt, Gross Unrealized Appreciation	802	1,522
Taxable, Gross Unrealized Appreciation	655	1,182
Total fixed maturities, Gross Unrealized Appreciation	1,457	2,704
Equity securities, Gross Unrealized Appreciation	756	453
Tax exempt, Gross Unrealized Depreciation	189	19
Taxable, Gross Unrealized Depreciation	136	7
Total fixed maturities, Gross Unrealized Depreciation	325	26
Equity securities, Gross Unrealized Depreciation	3	34
Tax exempt, Fair Value	18,421	19,913
Taxable, Fair Value	18,670	18,163
Total fixed maturities, Fair Value	37,091	38,076
Equity securities, Fair Value	1,810	1,663
U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Investment Holdings [Line Items]	'	'
Taxable, Amortized Cost	784	973
Taxable, Gross Unrealized Appreciation	27	66
Taxable, Gross Unrealized Depreciation	9	'
Taxable, Fair Value	802	1,039
Corporate Bonds [Member]	'	'
Investment Holdings [Line Items]	'	'
Taxable, Amortized Cost	9,032	7,331
Taxable, Gross Unrealized Appreciation	370	609
Taxable, Gross Unrealized Depreciation	88	3
Taxable, Fair Value	9,314	7,937
Foreign Government and Government Agency Obligations [Member]	'	'
Investment Holdings [Line Items]	'	'
Taxable, Amortized Cost	6,719	6,614
Taxable, Gross Unrealized Appreciation	206	395
Taxable, Gross Unrealized Depreciation	35	1
Taxable, Fair Value	6,890	7,008
Residential Mortgage-backed Securities [Member]	'	'
Investment Holdings [Line Items]	'	'
Taxable, Amortized Cost	277	421
Taxable, Gross Unrealized Appreciation	23	36
Taxable, Gross Unrealized Depreciation	1	2
Taxable, Fair Value	299	455
Commercial Mortgage-backed Securities [Member]	'	'
Investment Holdings [Line Items]	'	'
Taxable, Amortized Cost	1,339	1,649
Taxable, Gross Unrealized Appreciation	29	76
Taxable, Gross Unrealized Depreciation	3	1
Taxable, Fair Value	$1,365	$1,724

Invested_Assets_and_Related_In3

Invested Assets and Related Income - Summary of Fair Value of Tax Exempt Fixed Maturities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'
Fair value of the tax exempt fixed maturities	$18,421	$19,913
Tax Exempt Fixed Maturities [Member] | Special Revenue Bonds [Member]	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'
Fair value of the tax exempt fixed maturities	11,717	12,233
Tax Exempt Fixed Maturities [Member] | State General Obligation Bonds [Member]	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'
Fair value of the tax exempt fixed maturities	2,292	2,246
Tax Exempt Fixed Maturities [Member] | Municipal and Political Subdivision General Obligation Bonds [Member]	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'
Fair value of the tax exempt fixed maturities	2,220	2,505
Tax Exempt Fixed Maturities [Member] | Pre-Refunded Bonds [Member]	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'
Fair value of the tax exempt fixed maturities	$2,192	$2,929

Invested_Assets_and_Related_In4

Invested Assets and Related Income - Fair Value and Amortized Cost of Tax Exempt Fixed Maturities Other Than Pre-Refunded Bonds (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Texas [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	$1,990	$2,361
Amortized Cost	1,904	2,171
New York [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	1,839	1,603
Amortized Cost	1,809	1,487
California [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	1,139	1,189
Amortized Cost	1,093	1,089
Illinois [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	1,116	1,260
Amortized Cost	1,094	1,161
Florida [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	903	912
Amortized Cost	877	844
Special Revenue Bonds [Member] | Texas [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	930	1,041
Special Revenue Bonds [Member] | New York [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	1,611	1,401
Special Revenue Bonds [Member] | California [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	859	888
Special Revenue Bonds [Member] | Illinois [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	577	683
Special Revenue Bonds [Member] | Florida [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	757	771
Municipal and Political Subdivision General Obligation Bonds [Member] | Texas [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	830	1,053
Municipal and Political Subdivision General Obligation Bonds [Member] | New York [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	197	169
Municipal and Political Subdivision General Obligation Bonds [Member] | California [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	82	107
Municipal and Political Subdivision General Obligation Bonds [Member] | Illinois [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	483	518
Municipal and Political Subdivision General Obligation Bonds [Member] | Florida [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	38	27
State General Obligation Bonds [Member] | Texas [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	230	267
State General Obligation Bonds [Member] | New York [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	31	33
State General Obligation Bonds [Member] | California [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	198	194
State General Obligation Bonds [Member] | Illinois [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	56	59
State General Obligation Bonds [Member] | Florida [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	$108	$114

Invested_Assets_and_Related_In5

Invested Assets and Related Income - Fair Value and Amortized Cost of Foreign Government and Government Agency Fixed Maturities (Detail) (Foreign Government and Government Agency Obligations [Member], USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Canada [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	$1,993	$2,157
Amortized Cost	1,953	2,060
Germany [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	1,241	1,127
Amortized Cost	1,211	1,070
United Kingdom [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	1,026	1,024
Amortized Cost	1,004	939
Australia [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	739	742
Amortized Cost	700	663
Brazil [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Fair Value	270	310
Amortized Cost	$270	$310

Invested_Assets_and_Related_In6

Invested Assets and Related Income - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Investment
Schedule of Available-For-Sale Securities [Line Items]	'	'
Taxable, Fair Value	$18,670	$18,163
Approximate number of individual fixed maturities in unrealized loss position	1,160	'
Approximate number of individual equity securities in unrealized loss position	10	'
Cumulative credit-related losses recognized in net income	20	22
U S Government And Government Agencies And Authorities [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Taxable, Fair Value	802	1,039
Corporate Bond Securities [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Taxable, Fair Value	9,314	7,937
Foreign Government Debt [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Taxable, Fair Value	6,890	7,008
Supranational Organization Issued [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Taxable, Fair Value	$547	$517

Invested_Assets_and_Related_In7

Invested Assets and Related Income - Fair Value and Amortized Cost of Fixed Maturities by Contractual Maturity (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Schedule of Available-For-Sale Securities [Line Items]	'	'
Due in one year or less, Fair Value	$2,241	'
Due after one year through five years, Fair Value	13,769	'
Due after five years through ten years, Fair Value	11,743	'
Due after ten years, Fair Value	7,674	'
Subtotal fixed maturities, Fair Value	35,427	'
Total fixed maturities, Fair Value	37,091	38,076
Due in one year or less, Amortized Cost	2,212	'
Due after one year through five years, Amortized Cost	13,202	'
Due after five years through ten years, Amortized Cost	11,294	'
Due after ten years, Amortized Cost	7,635	'
Subtotal fixed maturities, Amortized Cost	34,343	'
Total fixed maturities, Amortized Cost	35,959	35,398
Residential Mortgage-backed Securities [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Taxable, Fair Value	299	'
Taxable, Amortized Cost	277	'
Commercial Mortgage-backed Securities [Member]	'	'
Schedule of Available-For-Sale Securities [Line Items]	'	'
Taxable, Fair Value	1,365	'
Taxable, Amortized Cost	$1,339	'

Invested_Assets_and_Related_In8

Invested Assets and Related Income - Components of Unrealized Appreciation or Depreciation of Investments (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Investments Debt And Equity Securities [Abstract]	'	'
Fixed maturities, Gross unrealized appreciation	$1,457	$2,704
Fixed maturities, Gross unrealized depreciation	325	26
Fixed maturities, Unrealized appreciation (depreciation), Net	1,132	2,678
Equity securities, Gross Unrealized Appreciation	756	453
Equity securities, Gross Unrealized Depreciation	3	34
Equity securities, Unrealized appreciation (depreciation), Net	753	419
Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net	1,885	3,097
Deferred income tax liability	660	1,084
Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net of tax	$1,225	$2,013

Invested_Assets_and_Related_In9

Invested Assets and Related Income - Fair Value and Gross Unrealized Depreciation of Investments in Unrealized Loss Position (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	$8,089	$1,378
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	262	31
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	692	236
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	66	29
Investment securities, Continuous unrealized loss position, Fair Value, Total	8,781	1,614
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	328	60
Fixed Maturities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	8,048	1,196
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	259	10
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	692	173
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	66	16
Investment securities, Continuous unrealized loss position, Fair Value, Total	8,740	1,369
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	325	26
Equity Securities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	41	182
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	3	21
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	'	63
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	'	13
Investment securities, Continuous unrealized loss position, Fair Value, Total	41	245
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	3	34
Tax Exempt [Member] | Fixed Maturities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	3,417	344
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	144	6
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	307	104
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	45	13
Investment securities, Continuous unrealized loss position, Fair Value, Total	3,724	448
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	189	19
Taxable [Member] | Fixed Maturities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	4,631	852
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	115	4
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	385	69
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	21	3
Investment securities, Continuous unrealized loss position, Fair Value, Total	5,016	921
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	136	7
Taxable [Member] | U.S. Government and Government Agency and Authority Obligations [Member] | Fixed Maturities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	213	28
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	6	'
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	35	20
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	3	'
Investment securities, Continuous unrealized loss position, Fair Value, Total	248	48
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	9	'
Taxable [Member] | Corporate Bonds [Member] | Fixed Maturities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	2,526	289
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	76	2
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	222	14
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	12	1
Investment securities, Continuous unrealized loss position, Fair Value, Total	2,748	303
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	88	3
Taxable [Member] | Foreign Government and Government Agency Obligations [Member] | Fixed Maturities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	1,735	429
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	32	1
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	75	13
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	3	'
Investment securities, Continuous unrealized loss position, Fair Value, Total	1,810	442
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	35	1
Residential Mortgage-backed Securities [Member] | Taxable [Member] | Fixed Maturities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	4	1
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	'	'
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	14	19
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	1	2
Investment securities, Continuous unrealized loss position, Fair Value, Total	18	20
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	1	2
Commercial Mortgage-backed Securities [Member] | Taxable [Member] | Fixed Maturities [Member]	'	'
Investment Holdings [Line Items]	'	'
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	153	105
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	1	1
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	39	3
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	2	'
Investment securities, Continuous unrealized loss position, Fair Value, Total	192	108
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	$3	$1

Recovered_Sheet1

Invested Assets and Related Income - Change in Unrealized Appreciation or Depreciation of Investments Carried at Fair Value (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments Debt And Equity Securities [Abstract]	'	'	'
Change in unrealized appreciation of fixed maturities	($1,546)	$256	$964
Change in unrealized appreciation of equity securities	334	171	-17
Change in unrealized appreciation of fixed maturities and equity securities	-1,212	427	947
Deferred income tax (credit)	-424	150	331
Total change in unrealized appreciation (depreciation) of fixed maturities and equity securities, Net of tax	($788)	$277	$616

Recovered_Sheet2

Invested Assets and Related Income - Sources of Net Investment Income (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'	'	'
Gross investment income	$1,465	$1,556	$1,644
Investment Expenses	49	38	39
Net Investment income	1,416	1,518	1,605
Fixed Maturities [Member]	'	'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'	'	'
Gross investment income	1,380	1,465	1,549
Equity Securities [Member]	'	'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'	'	'
Gross investment income	38	40	34
Short Term Investments [Member]	'	'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'	'	'
Gross investment income	16	18	16
Other [Member]	'	'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'	'	'
Gross investment income	$31	$33	$45

Recovered_Sheet3

Invested Assets and Related Income - Realized Investment Gains and Losses (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments Debt And Equity Securities [Abstract]	'	'	'
Fixed maturities, Gross realized gains	$62	$124	$70
Fixed maturities, Gross realized losses	-42	-20	-39
Fixed maturities, Other-than-temporary impairment losses	-2	-5	-1
Total fixed maturities	18	99	30
Equity securities, Gross realized gains	204	68	74
Equity securities, Gross realized losses	-1	'	-1
Equity securities, Other-than-temporary impairment losses	-9	-40	-22
Total equity securities	194	28	51
Other invested assets	190	66	207
Total Realized Investment Gains, Net	$402	$193	$288

Deferred_Policy_Acquisition_Co2

Deferred Policy Acquisition Costs - Policy Acquisition Costs Deferred and Related Amortization Reflected in Operating Results (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]	'	'	'
Balance, beginning of year	$1,206	$1,210	$1,142
Costs deferred during year	'	'	'
Commissions and brokerage	1,979	1,919	1,910
Premium taxes and assessments	263	247	235
Underwriting and policy issuance costs	271	248	248
Total costs deferred during year	2,513	2,414	2,393
Foreign currency translation effect	-10	-7	5
Amortization during year	-2,454	-2,411	-2,330
Balance, end of year	$1,255	$1,206	$1,210

Property_and_Equipment_Schedul

Property and Equipment - Schedule of Property and Equipment (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Property Plant And Equipment [Abstract]	'	'
Cost	$501	$517
Accumulated depreciation	243	248
Property and Equipment, net of accumulated depreciation	$258	$269

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property Plant And Equipment [Abstract]	'	'	'
Depreciation expense related to property and equipment	$55	$54	$58

Unpaid_Losses_and_Loss_Expense2

Unpaid Losses and Loss Expenses - Reconciliation of Beginning and Ending Liability for Unpaid Losses and Loss Expenses (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Insurance [Abstract]	'	'	'
Gross liability, beginning of year	$23,963	$23,068	$22,718
Reinsurance recoverable, beginning of year	1,941	1,739	1,817
Net liability, beginning of year	22,022	21,329	20,901
Net incurred losses and loss expenses related to [Abstract]	'	'	'
Current year	7,232	8,121	8,174
Prior years	-712	-614	-767
Net incurred losses and loss expenses, total	6,520	7,507	7,407
Net payments for losses and loss expenses related to [Abstract]	'	'	'
Current year	2,150	2,323	2,746
Prior years	4,952	4,493	4,300
Net payments for losses and loss expenses, total	7,102	6,816	7,046
Foreign currency translation effect	-96	2	67
Net liability, end of year	21,344	22,022	21,329
Reinsurance recoverable, end of year	1,802	1,941	1,739
Gross liability, end of year	$23,146	$23,963	$23,068

Unpaid_Losses_and_Loss_Expense3

Unpaid Losses and Loss Expenses - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Manufacturers_Distributors
Insurance [Abstract]	'	'	'
Favorable development on net unpaid losses and loss expenses established as of the previous year end	$712	$614	$767
Aggregate favorable development experienced in the personal and commercial liability classes	265	250	355
Amount related to catastrophes	30	'	'
Favorable development experienced in the professional liability classes other than fidelity	260	200	310
Aggregate favorable development experienced in the personal and commercial property classes	160	125	80
Adverse development for losses related to asbestos and toxic waste claims	106	83	72
Adverse development experienced in the fidelity class	50	60	70
Favorable development experienced in the personal automobile business	35	40	30
Favorable development experienced in the surety business	30	25	15
Favorable development experienced in the runoff of the reinsurance assumed business	'	$45	$30
Number of manufacturers and distributors of asbestos products that filed for bankruptcy protection	100	'	'

Debt_and_Credit_Arrangements_L

Debt and Credit Arrangements - Long Term Debt (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Debt Instrument [Line Items]	'	'
Long Term Debt	$3,300	$3,575
5.2% notes due April 1, 2013 [Member]	'	'
Debt Instrument [Line Items]	'	'
Long Term Debt	'	275
5.75% notes due May 15, 2018 [Member]	'	'
Debt Instrument [Line Items]	'	'
Long Term Debt	600	600
6.6% debentures due August 15, 2018 [Member]	'	'
Debt Instrument [Line Items]	'	'
Long Term Debt	100	100
6.8% debentures due November 15, 2031 [Member]	'	'
Debt Instrument [Line Items]	'	'
Long Term Debt	200	200
6% notes due May 11, 2037 [Member]	'	'
Debt Instrument [Line Items]	'	'
Long Term Debt	800	800
6.5% notes due May 15, 2038 [Member]	'	'
Debt Instrument [Line Items]	'	'
Long Term Debt	600	600
6.375% capital securities due March 29, 2067 [Member]	'	'
Debt Instrument [Line Items]	'	'
Long Term Debt	$1,000	$1,000

Debt_and_Credit_Arrangements_L1

Debt and Credit Arrangements - Long Term Debt (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2013
Debt Instrument [Line Items]	'
Interest rate of capital securities march 29, 2067	6.38%
5.2% notes due April 1, 2013 [Member]	'
Debt Instrument [Line Items]	'
Interest rate due on notes and debentures	5.20%
5.75% notes due May 15, 2018 [Member]	'
Debt Instrument [Line Items]	'
Interest rate due on notes and debentures	5.75%
6.6% debentures due August 15, 2018 [Member]	'
Debt Instrument [Line Items]	'
Interest rate due on notes and debentures	6.60%
6.8% debentures due November 15, 2031 [Member]	'
Debt Instrument [Line Items]	'
Interest rate due on notes and debentures	6.80%
6% notes due May 11, 2037 [Member]	'
Debt Instrument [Line Items]	'
Interest rate due on notes and debentures	6.00%
6.5% notes due May 15, 2038 [Member]	'
Debt Instrument [Line Items]	'
Interest rate due on notes and debentures	6.50%
6.375% capital securities due March 29, 2067 [Member]	'
Debt Instrument [Line Items]	'
Interest rate of capital securities march 29, 2067	6.38%

Debt_and_Credit_Arrangements_A

Debt and Credit Arrangements - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]	'	'	'
Long Term Debt	$3,300	$3,575	'
Interest rate of capital securities through April 14, 2017	6.38%	'	'
Interest rate on capital securities after April 14, 2017, plus three-month LIBOR rate	2.25%	'	'
Consecutive years payment of interest may be deferred on capital securities	'10 years	'	'
Interest costs incurred	213	224	245
Interest paid	213	220	244
Maximum unsecured borrowings permitted under credit agreement	500	500	'
Maximum facility amount permitted to request an increase in the credit available	750	'	'
6.375% capital securities due March 29, 2067 [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Long Term Debt	1,000	1,000	'
Interest rate of capital securities through April 14, 2017	6.38%	'	'
6.8% debentures due November 15, 2031 [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Long Term Debt	$200	$200	'
Interest rate due on notes and debentures	6.80%	'	'

Debt_and_Credit_Arrangements_A1

Debt and Credit Arrangements - Amounts of Long Term Debt due Annually (Detail) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Debt Disclosure [Abstract]	'
2014	'
2015	'
2016	'
2017	'
2018	$700

Federal_and_Foreign_Income_Tax2

Federal and Foreign Income Tax - Income Tax Expense and Taxes Paid (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income tax expense and taxes paid	'	'	'	'	'	'	'	'	'	'	'
Current tax, United States	'	'	'	'	'	'	'	'	$791	$276	$260
Current tax, Foreign	'	'	'	'	'	'	'	'	91	143	236
Deferred tax, principally United States	'	'	'	'	'	'	'	'	10	32	25
Federal and foreign income tax	217	198	217	260	-39	194	123	173	892	451	521
Federal and foreign income taxes paid	'	'	'	'	'	'	'	'	$789	$472	$598

Federal_and_Foreign_Income_Tax3

Federal and Foreign Income Tax - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Income before federal and foreign income taxes from U.S operations	$2,766	$1,373	$1,666
Income before federal and foreign income taxes from foreign operations	471	623	533
Deferred income tax asset valuation allowance	$13	$12	'

Federal_and_Foreign_Income_Tax4

Federal and Foreign Income Tax - Reconciliation of Effective Income Tax Rate and Statutory Federal Corporate Tax Rate (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Income before federal and foreign income tax	'	'	'	'	'	'	'	'	$3,237	$1,996	$2,199
Tax at statutory federal income tax rate	'	'	'	'	'	'	'	'	1,133	699	770
Tax exempt interest income	'	'	'	'	'	'	'	'	-222	-233	-243
Other, net	'	'	'	'	'	'	'	'	-19	-15	-6
Federal and foreign income tax	$217	$198	$217	$260	($39)	$194	$123	$173	$892	$451	$521
Income before federal and foreign income tax, percentage of pre-tax income	'	'	'	'	'	'	'	'	'	'	'
Tax at statutory federal income tax rate, percentage of pre-tax income	'	'	'	'	'	'	'	'	35.00%	35.00%	35.00%
Tax exempt interest income, percentage of pre-tax income	'	'	'	'	'	'	'	'	-6.80%	-11.70%	-11.00%
Other, net, percentage of pre-tax income	'	'	'	'	'	'	'	'	-0.60%	-0.70%	-0.30%
Actual tax, percentage of pre-tax income	'	'	'	'	'	'	'	'	27.60%	22.60%	23.70%

Federal_and_Foreign_Income_Tax5

Federal and Foreign Income Tax - Tax Effects of Temporary Differences that Gave Rise to Deferred Income Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Deferred income tax assets	'	'
Unpaid losses and loss expenses	$524	$605
Unearned premiums	350	341
Foreign tax credits	867	870
Employee compensation	142	119
Postretirement benefits	95	324
Other-than-temporary impairment losses	291	294
Total deferred income tax assets	2,269	2,553
Deferred income tax liabilities	'	'
Deferred policy acquisition costs	356	341
Unremitted earnings of foreign subsidiaries	970	951
Unrealized appreciation of investments	660	1,084
Other invested assets	184	225
Other, net	52	114
Total deferred income tax liabilities	2,222	2,715
Net deferred income tax asset (liability)	$47	($162)

Reinsurance_Effect_of_Reinsura

Reinsurance - Effect of Reinsurance on Premiums Written and Earned (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Insurance [Abstract]	'	'	'
Direct premiums written	$12,804	$12,647	$12,452
Assumed reinsurance	503	423	398
Ceded reinsurance	-1,083	-1,200	-1,092
Net premiums written	12,224	11,870	11,758
Direct premiums earned	12,717	12,596	12,387
Assumed reinsurance	476	422	365
Ceded reinsurance	-1,127	-1,180	-1,108
Net premiums earned	$12,066	$11,838	$11,644

Reinsurance_Additional_Informa

Reinsurance - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Insurance [Abstract]	'	'	'
Ceded losses and loss expenses incurred	$400	$586	$308

StockBased_Employee_Compensati2

Stock-Based Employee Compensation Plans - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Compensation cost related to stock-based compensation plan	$89	$84	$82
Total income tax benefit related to stock-based compensation plan	31	29	29
Unrecognized compensation cost related to nonvested awards	80	'	'
Weighted average period of years over which unrecognized compensation cost will be reflected in operating results	'1 year 9 months 18 days	'	'
Maximum number of shares in respect to which stock-based awards may be granted under the plan most recently approved by shareholders	8,650,000	'	'
Shares available for grant	6,891,434	'	'
Performance period in which performance unit awards are based	'3 years	'	'
Stock option expiration period	'10 years	'	'
Weighted average fair value per stock option granted	$14.95	$11.95	$11.55
Total intrinsic value of stock options exercised	16	40	35
Cash received from the exercise of stock options	10	47	53
Tax benefit realized with respect to the exercise of stock options	5	13	11
Restricted Stock Units [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Weighted average fair value per share of the restricted stock units and performance units granted	$83.75	$68.64	$60.58
Total fair value of the restricted stock units and performance units vested	72	74	59
Performance Units [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Weighted average fair value per share of the restricted stock units and performance units granted	$98.46	$63.38	$64.34
Total fair value of the restricted stock units and performance units vested	$64	$70	$47

StockBased_Employee_Compensati3

Stock-Based Employee Compensation Plans - Additional Information With Respect to Restricted Stock Units and Performance Units (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Restricted Stock Units (RSUs) [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Number of Shares, Nonvested, January 1, 2013	2,418,946
Number of Shares, Granted	668,754
Number of Shares, Vested	-852,786
Number of Shares, Forfeited	-107,267
Number of Shares, Nonvested, December 31, 2013	2,127,647
Weighted Average Grant Date Fair Value on Number of Shares, Nonvested, January 1, 2013	$59.54
Weighted Average Grant Date Fair Value on Number of Shares, Granted	$83.75
Weighted Average Grant Date Fair Value on Number of Shares, Vested	$51.42
Weighted Average Grant Date Fair Value on Number of Shares, Forfeited	$63
Weighted Average Grant Date Fair Value on Number of Shares, Nonvested, December 31, 2013	$70.23
Performance Units [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Number of Shares, Nonvested, January 1, 2013	973,909
Number of Shares, Granted	408,989
Number of Shares, Vested	-500,409
Number of Shares, Forfeited	-21,348
Number of Shares, Nonvested, December 31, 2013	861,141
Weighted Average Grant Date Fair Value on Number of Shares, Nonvested, January 1, 2013	$63.88
Weighted Average Grant Date Fair Value on Number of Shares, Granted	$98.46
Weighted Average Grant Date Fair Value on Number of Shares, Vested	$64.34
Weighted Average Grant Date Fair Value on Number of Shares, Forfeited	$70.58
Weighted Average Grant Date Fair Value on Number of Shares, Nonvested, December 31, 2013	$79.87

StockBased_Employee_Compensati4

Stock-Based Employee Compensation Plans - Additional Information With Respect to Restricted Stock Units and Performance Units (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Percentage of number of shares that may be earned related to performance units, Minimum	0.00%
Percentage of number of shares that may be earned related to performance units, Maximum	200.00%
Percentage of performance units earned as it relates to vested shares	132.60%
Number of performance units earned as it relates to vested shares	663,542

StockBased_Employee_Compensati5

Stock-Based Employee Compensation Plans - Stock Option Pricing Weighted Average Assumptions (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'
Risk-free interest rate	0.90%	1.00%	2.40%
Expected volatility	24.40%	24.60%	24.20%
Dividend yield	2.10%	2.40%	2.60%
Expected average term (in years)	'5 years 6 months	'5 years 6 months	'5 years 6 months

StockBased_Employee_Compensati6

Stock-Based Employee Compensation Plans - Additional Information With Respect to Stock Options (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Number of Shares Outstanding, January 1, 2013	520,575
Number of Shares, Granted	71,903
Number of Shares, Exercised	-317,256
Number of Shares, Forfeited	-23,535
Number of Shares Outstanding, December 31, 2013	251,687
Number of Shares Exercisable, December 31, 2013	127,475
Weighted Average Exercise Price on Number of Shares Outstanding, January 1, 2013	$40.24
Weighted Average Exercise Price on Number of Shares, Granted	$83.89
Weighted Average Exercise Price on Number of Shares, Exercised	$32.48
Weighted Average Exercise Price on Number of Shares, Forfeited	$39.94
Weighted Average Exercise Price on Number of Shares Outstanding, December 31, 2013	$62.52
Weighted Average Exercise Price on Number of Shares Exercisable, December 31, 2013	$48.93
Weighted Average Remaining Contractual Term (in years) on Number of Shares Outstanding	'6 years 7 months 6 days
Weighted Average Remaining Contractual Term (in years) on Number of Shares Exercisable, December 31, 2013	'4 years 8 months 12 days
Aggregate Intrinsic Value on Number of Shares Outstanding, December 31, 2013	$9
Aggregate Intrinsic Value on Number of Shares Exercisable, December 31, 2013	$6

Employee_Benefits_Funded_Statu

Employee Benefits - Funded Status of Pension and Other Postretirement Benefit Plans (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan assets at fair value	$2,717	$2,305	'
Pension Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Benefit obligation, beginning of year	2,894	2,494	'
Service cost	95	88	79
Interest cost	125	124	120
Actuarial loss (gain)	-261	256	'
Benefits paid	-75	-74	'
Foreign currency translation effect	-1	6	'
Benefit obligation, end of year	2,777	2,894	2,494
Plan assets at fair value	2,717	2,305	'
Funded status at end of year, included in other liabilities	60	589	'
Other Postretirement Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Benefit obligation, beginning of year	470	454	'
Service cost	13	12	11
Interest cost	19	20	22
Actuarial loss (gain)	-97	-4	'
Benefits paid	-11	-12	'
Foreign currency translation effect	'	'	'
Benefit obligation, end of year	394	470	454
Plan assets at fair value	130	96	'
Funded status at end of year, included in other liabilities	$264	$374	'

Employee_Benefits_Net_Actuaria

Employee Benefits - Net Actuarial Loss (Gain) and Prior Service Cost Included in Accumulated Other Comprehensive Income (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Pension Benefits [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Net actuarial loss (gain)	$396	$989
Prior service cost	16	18
Total net actuarial loss and prior service cost included in accumulated other comprehensive income	412	1,007
Other Postretirement Benefits [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Net actuarial loss (gain)	-13	108
Prior service cost	1	'
Total net actuarial loss and prior service cost included in accumulated other comprehensive income	($12)	$108

Employee_Benefits_Additional_I

Employee Benefits - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Accumulated benefit obligation for the pension plans	$2,381	$2,479	'
Estimated aggregate net actuarial loss and prior service cost to be amortized next year	34	'	'
Effect of one percent increase in health care cost trend rate on the accumulated other postretirement benefit obligation	67	'	'
Effect of one percent decrease in health care cost trend rate on the accumulated other postretirement benefit obligation	53	'	'
Effect of one percent increase in health care cost trend rate on net other postretirement benefit cost	6	'	'
Effect of one percent decrease in health care cost trend rate on net other postretirement benefit cost	5	'	'
Employer annual elective matching contribution related to employee's eligible pre-tax contributions	'Equal to 100%	'	'
The portion of employer annual elective matching contribution related to employee's eligible pre-tax contributions	'Up to 4%	'	'
Employer contributions for Capital Accumulation Plan	29	26	27
Equity Securities [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Minimum range of portfolio allocation to equity securities	55.00%	'	'
Maximum range of portfolio allocation to equity securities	65.00%	'	'
Pension Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Employer contributions	74	98	'
Fair value of plan assets invested in pooled funds	1,425	1,200	'
Other Postretirement Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Employer contributions	10	10	'
Fair value of plan assets invested in pooled funds	$130	$96	'

Employee_Benefits_Weighted_Ave

Employee Benefits - Weighted Average Assumptions Used to Determine Benefit Obligations (Detail)	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Discount rate	5.20%	4.40%
Rate of compensation increase	4.50%	4.50%
Other Postretirement Benefits [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Discount rate	5.20%	4.40%
Rate of compensation increase	'	'

Employee_Benefits_Components_o

Employee Benefits - Components of Net Pension and Other Postretirement Benefit Costs Reflected in Net Income (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits [Member]	'	'	'
Components of net pension and other postretirement benefit costs reflected in net income	'	'	'
Service cost	$95	$88	$79
Interest cost	125	124	120
Expected return on plan assets	-165	-155	-140
Amortization of net actuarial loss and prior service cost and other	90	80	68
Total benefit costs reflected in net income	145	137	127
Other Postretirement Benefits [Member]	'	'	'
Components of net pension and other postretirement benefit costs reflected in net income	'	'	'
Service cost	13	12	11
Interest cost	19	20	22
Expected return on plan assets	-7	-6	-5
Amortization of net actuarial loss and prior service cost and other	3	3	3
Total benefit costs reflected in net income	$28	$29	$31

Employee_Benefits_Changes_in_P

Employee Benefits - Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits [Member]	'	'	'
Changes in plan assets and benefit obligations recognized in other comprehensive income	'	'	'
Net actuarial loss (gain)	($505)	$139	$355
Amortization of net actuarial loss and prior service cost and other	-90	-80	-68
Total changes in plan assets and benefit obligations recognized in other comprehensive income	-595	59	287
Other Postretirement Benefits [Member]	'	'	'
Changes in plan assets and benefit obligations recognized in other comprehensive income	'	'	'
Net actuarial loss (gain)	-117	-11	45
Amortization of net actuarial loss and prior service cost and other	-3	-3	-3
Total changes in plan assets and benefit obligations recognized in other comprehensive income	($120)	($14)	$42

Employee_Benefits_Weighted_Ave1

Employee Benefits - Weighted Average Assumptions Used to Determine Net Pension and Other Postretirement Benefit Costs (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Discount rate	4.40%	5.00%	5.75%
Rate of compensation increase	4.50%	4.50%	4.50%
Expected long term rate of return on plan assets	7.50%	7.75%	7.75%
Other Postretirement Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Discount rate	4.40%	5.00%	5.75%
Rate of compensation increase	'	'	'
Expected long term rate of return on plan assets	7.50%	7.75%	7.75%

Employee_Benefits_Weighted_Ave2

Employee Benefits - Weighted Average Health Care Cost Trend Rate Assumptions (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Compensation And Retirement Disclosure [Abstract]	'	'
Health care cost trend rate for next year	7.60%	7.90%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	4.50%	4.50%
Year that the rate reaches the ultimate trend rate	'2028	'2028

Employee_Benefits_Fair_Values_

Employee Benefits - Fair Values of Pension Plan Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	$2,717	$2,305
Short Term Investments [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	37	33
Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	916	814
Equity Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	1,718	1,404
Mortgage Backed Securities [Member] | Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	217	174
U.S. Government and Government Agency and Authority Obligations [Member] | Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	224	239
Corporate Bonds [Member] | Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	371	321
Foreign Government and Government Agency Obligations [Member] | Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	104	80
Other Assets [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	$46	$54

Employee_Benefits_Estimated_Be

Employee Benefits - Estimated Benefits Expected to be Paid (Detail) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Pension Benefits [Member]	'
Defined Benefit Plan Disclosure [Line Items]	'
2014	$99
2015	104
2016	114
2017	149
2018	130
2019-2023	803
Other Postretirement Benefits [Member]	'
Defined Benefit Plan Disclosure [Line Items]	'
2014	12
2015	13
2016	15
2017	16
2018	18
2019-2023	$114

Comprehensive_Income_Component

Comprehensive Income - Components of Other Comprehensive Income or Loss (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]	'	'	'
Net unrealized holding gains (losses)arising during the year, Before Tax	($1,000)	$556	$1,029
Unrealized other-than-temporary impairment losses arising during the year, Before Tax	'	-2	-1
Reclassification adjustment for net realized gains included in net income, Before tax	212	127	81
Net unrealized gains (losses) recognized in other comprehensive income or loss, Before Tax	-1,212	427	947
Postretirement benefit gain (loss) not yet recognized in net income arising during the year, Before Tax	622	-128	-400
Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income, Before Tax	-93	-83	-71
Net change in postretirement benefit costs not yet recognized in net income, Before Tax	715	-45	-329
Foreign currency translation gains (losses), Before Tax	-111	-16	6
Total other comprehensive income (loss), Before Tax	-608	366	624
Net unrealized holding gains (losses) arising during the year, Income Tax	-350	195	359
Unrealized other-than-temporary impairment losses arising during the year, Income Tax	'	-1	'
Reclassification adjustment for net realized gains included in net income, Income Tax	74	44	28
Net unrealized gains (losses) recognized in other comprehensive income or loss, Income Tax	-424	150	331
Postretirement benefit gain (loss) not yet recognized in net income arising during the year, Income Tax	218	-45	-140
Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income, Income Tax	-33	-30	-26
Net change in postretirement benefit costs not yet recognized in net income, Income Tax	251	-15	-114
Foreign currency translation gains (losses), Income Tax	-39	-5	2
Total other comprehensive income (loss), Income Tax	-212	130	219
Net unrealized holding losses arising during the period, Net of Tax	-650	361	670
Unrealized other-than-temporary impairment losses arising during the year, Net of Tax	'	-1	-1
Reclassification adjustment for net realized gains included in net income, Net of Tax	138	83	53
Net unrealized gains (losses) recognized in other comprehensive income or loss, Net of Tax	-788	277	616
Postretirement benefit gain (loss) not yet recognized in net income arising during the period, Net of Tax	404	-83	-260
Reclassification adjustment for the amortization of net actuarial loss and prior service cost, Net of Tax	-60	-53	-45
Net change in postretirement benefit costs not yet recognized in net income, Net of Tax	464	-30	-215
Foreign currency translation gains (losses), Net of Tax	-72	-11	4
Total Other Comprehensive Income (Loss) Net of Tax	($396)	$236	$405

Commitments_and_Contingent_Lia2

Commitments and Contingent Liabilities - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Commitments And Contingencies Disclosure [Abstract]	'	'
Notional amount of future obligations under Chubb Financial Solutions' (CFS) derivative contracts	$80	$90
Fair value of future obligations under Chubb Financial Solutions' derivative contracts	2	2
Aggregate principal commitments related to a reinsurance contract for which a property and casualty insurance subsidiary was contingently liable	380	'
Year of expiration of principal commitments related to a reinsurance contract written by a property and casualty subsidiary	'2023	'
Year through which office facilities under lease agreements will expire	'2029	'
Office facility leases renewal options in years, Lower end of range	'2 years	'
Office facility leases renewal options in years, Higher end of range	'10 years	'
Commitments to fund limited partnership investments	$660	'
Period for which commitments can be called by the partnerships	'5 years or less	'

Commitments_and_Contingent_Lia3

Commitments and Contingent Liabilities - Rent Expense (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]	'	'	'
Rent expense	$84	$82	$83
Office facilities [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Rent expense	71	71	73
Equipment [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Rent expense	$13	$11	$10

Commitments_and_Contingent_Lia4

Commitments and Contingent Liabilities - Future Minimum Rental Payments Required Under Non-Cancellable Operating Leases (Detail) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]	'
2014	$67
2015	59
2016	47
2017	37
2018	32
After 2018	74
Total	$316

Segments_Information_Additiona

Segments Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013
	Operations
	Business_Unit
Segment Reporting [Abstract]	'
Number of segment operations	2
Number of business units	4

Segments_Information_Revenues_

Segments Information - Revenues, Income Before Income Tax and Assets of Each Operating Segment (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues	'	'	'	'	'	'	'	'	'	'	'
Premiums earned related to insurance business	'	'	'	'	'	'	'	'	$12,069	$11,834	$11,631
Investment Income	'	'	'	'	'	'	'	'	1,465	1,556	1,644
Premiums earned related to reinsurance assumed	'	'	'	'	'	'	'	'	-3	4	13
Net Premiums earned	'	'	'	'	'	'	'	'	12,066	11,838	11,644
Corporate and other	'	'	'	'	'	'	'	'	43	46	55
Realized investment gains, net	'	'	'	'	'	'	'	'	402	193	288
Total Revenues	3,476	3,403	3,551	3,517	3,400	3,362	3,423	3,410	13,947	13,595	13,585
Insurance underwriting income (loss)	'	'	'	'	'	'	'	'	1,607	498	475
Reinsurance assumed underwriting income	'	'	'	'	'	'	'	'	9	47	36
Underwriting income before deferred policy acquisition costs	'	'	'	'	'	'	'	'	1,616	545	511
Increase in deferred policy acquisition costs	'	'	'	'	'	'	'	'	59	3	63
Underwriting income	'	'	'	'	'	'	'	'	1,675	548	574
Investment income	'	'	'	'	'	'	'	'	1,416	1,518	1,605
Total property and casualty insurance	'	'	'	'	'	'	'	'	3,072	2,040	2,157
Corporate and other	'	'	'	'	'	'	'	'	-237	-237	-246
Realized investment gains, net	'	'	'	'	'	'	'	'	402	193	288
INCOME BEFORE FEDERAL AND FOREIGN INCOME TAX	'	'	'	'	'	'	'	'	3,237	1,996	2,199
Assets	'	'	'	'	'	'	'	'	'	'	'
Total assets	50,433	'	'	'	52,184	'	'	'	50,433	52,184	50,445
Property and casualty insurance [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	'	'	'	'	'
Investment Income	'	'	'	'	'	'	'	'	1,436	1,518	1,598
Total Revenues	'	'	'	'	'	'	'	'	13,502	13,356	13,242
Investment income	'	'	'	'	'	'	'	'	1,391	1,482	1,562
Other income	'	'	'	'	'	'	'	'	6	10	21
Operating Segments [Member]	'	'	'	'	'	'	'	'	'	'	'
Assets	'	'	'	'	'	'	'	'	'	'	'
Total assets	48,278	'	'	'	49,441	'	'	'	48,278	49,441	48,017
Operating Segments [Member] | Personal insurance [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	'	'	'	'	'
Premiums earned related to insurance business	'	'	'	'	'	'	'	'	4,214	4,024	3,917
Insurance underwriting income (loss)	'	'	'	'	'	'	'	'	509	192	47
Operating Segments [Member] | Commercial insurance [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	'	'	'	'	'
Premiums earned related to insurance business	'	'	'	'	'	'	'	'	5,237	5,144	4,945
Insurance underwriting income (loss)	'	'	'	'	'	'	'	'	692	44	1
Operating Segments [Member] | Specialty insurance [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	'	'	'	'	'
Premiums earned related to insurance business	'	'	'	'	'	'	'	'	2,618	2,666	2,769
Insurance underwriting income (loss)	'	'	'	'	'	'	'	'	406	262	427
Corporate and other [Member]	'	'	'	'	'	'	'	'	'	'	'
Assets	'	'	'	'	'	'	'	'	'	'	'
Total assets	2,248	'	'	'	2,830	'	'	'	2,248	2,830	2,513
Adjustments and eliminations [Member]	'	'	'	'	'	'	'	'	'	'	'
Assets	'	'	'	'	'	'	'	'	'	'	'
Total assets	($93)	'	'	'	($87)	'	'	'	($93)	($87)	($85)

Segments_Information_Revenues_1

Segments Information - Revenues of Property and Casualty Group by Geographic Area (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues by geographic area	'	'	'	'	'	'	'	'	'	'	'
Revenues	$3,476	$3,403	$3,551	$3,517	$3,400	$3,362	$3,423	$3,410	$13,947	$13,595	$13,585
P&C Group [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues by geographic area	'	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	'	'	13,502	13,356	13,242
P&C Group [Member] | Reportable Geographical Components [Member] | United States [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues by geographic area	'	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	'	'	10,205	9,996	9,831
P&C Group [Member] | Reportable Geographical Components [Member] | International [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues by geographic area	'	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	'	'	$3,297	$3,360	$3,411

Fair_Values_of_Financial_Instr2

Fair Values of Financial Instruments - Carrying Values and Fair Values of Financial Instruments (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Short Term Investments	$2,114	$2,528
Fixed maturities	37,091	38,076
Equity securities	1,810	1,663
Other Invested Assets	1,598	1,954
Long Term Debt	3,300	3,575
Carrying Value [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Short Term Investments	2,114	2,528
Fixed maturities	37,091	38,076
Equity securities	1,810	1,663
Other Invested Assets	'	46
Long Term Debt	3,300	3,575
Fair Value [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Short Term Investments	2,114	2,528
Fixed maturities	37,091	38,076
Equity securities	1,810	1,663
Other Invested Assets	'	46
Long Term Debt	$3,806	$4,372

Fair_Values_of_Financial_Instr3

Fair Values of Financial Instruments - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Defined Benefit Plan Disclosure [Line Items]	'	'
Percentage of fair value amounts for fixed maturities provided by a pricing service	99.00%	99.00%
Plan assets at fair value	$2,717	$2,305
Other Postretirement Benefits [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	$130	$96

Fair_Values_of_Financial_Instr4

Fair Values of Financial Instruments - Fair Value of Financial Instruments Categorized Based Upon Lowest Level of Input (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Short Term Investments	$2,114	$2,528
Tax exempt, Fair Value	18,421	19,913
Taxable, Fair Value	18,670	18,163
Total fixed maturities, Fair Value	37,091	38,076
Equity securities	1,810	1,663
Other Invested Assets	1,598	1,954
Long Term Debt	3,300	3,575
Residential Mortgage Backed Securities [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	299	455
Commercial Mortgage Backed Securities [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	1,365	1,724
U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	802	1,039
Corporate Bonds [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	9,314	7,937
Foreign Government and Government Agency Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	6,890	7,008
Fair value [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Short Term Investments	2,114	2,528
Tax exempt, Fair Value	18,421	19,913
Taxable, Fair Value	18,670	18,163
Total fixed maturities, Fair Value	37,091	38,076
Equity securities	1,810	1,663
Other Invested Assets	'	46
Total fixed maturities, equity securities and other invested assets, Fair Value	41,015	42,313
Long Term Debt	3,806	4,372
Fair value [Member] | U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	802	1,039
Fair value [Member] | Corporate Bonds [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	9,314	7,937
Fair value [Member] | Foreign Government and Government Agency Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	6,890	7,008
Residential Mortgage-backed Securities [Member] | Fair value [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	299	455
Commercial Mortgage-backed Securities [Member] | Fair value [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	1,365	1,724
Level 1 [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Short Term Investments	399	182
Tax exempt, Fair Value	'	'
Taxable, Fair Value	'	'
Total fixed maturities, Fair Value	'	'
Equity securities	1,803	1,655
Other Invested Assets	'	'
Total fixed maturities, equity securities and other invested assets, Fair Value	2,202	1,837
Long Term Debt	'	'
Level 1 [Member] | U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	'	'
Level 1 [Member] | Corporate Bonds [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	'	'
Level 1 [Member] | Foreign Government and Government Agency Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	'	'
Level 1 [Member] | Residential Mortgage-backed Securities [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	'	'
Level 1 [Member] | Commercial Mortgage-backed Securities [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	'	'
Level 2 [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Short Term Investments	1,715	2,346
Tax exempt, Fair Value	18,416	19,907
Taxable, Fair Value	18,500	17,996
Total fixed maturities, Fair Value	36,916	37,903
Equity securities	'	'
Other Invested Assets	'	'
Total fixed maturities, equity securities and other invested assets, Fair Value	38,631	40,249
Long Term Debt	3,806	4,372
Level 2 [Member] | U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	802	1,039
Level 2 [Member] | Corporate Bonds [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	9,179	7,779
Level 2 [Member] | Foreign Government and Government Agency Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	6,881	7,008
Level 2 [Member] | Residential Mortgage-backed Securities [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	293	446
Level 2 [Member] | Commercial Mortgage-backed Securities [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	1,345	1,724
Level 3 [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Short Term Investments	'	'
Tax exempt, Fair Value	5	6
Taxable, Fair Value	170	167
Total fixed maturities, Fair Value	175	173
Equity securities	7	8
Other Invested Assets	'	46
Total fixed maturities, equity securities and other invested assets, Fair Value	182	227
Long Term Debt	'	'
Level 3 [Member] | U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	'	'
Level 3 [Member] | Corporate Bonds [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	135	158
Level 3 [Member] | Foreign Government and Government Agency Obligations [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	9	'
Level 3 [Member] | Residential Mortgage-backed Securities [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	6	9
Level 3 [Member] | Commercial Mortgage-backed Securities [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Taxable, Fair Value	$20	'

Fair_Values_of_Financial_Instr5

Fair Values of Financial Instruments - Fair Values of Pension Plan Assets Categorized Based Upon Lowest Level of Input (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	$2,717	$2,305
Short Term Investments [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	37	33
Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	916	814
Fixed Maturities [Member] | U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	224	239
Fixed Maturities [Member] | Corporate Bonds [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	371	321
Fixed Maturities [Member] | Foreign Government and Government Agency Obligations [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	104	80
Fixed Maturities [Member] | Mortgage Backed Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	217	174
Equity Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	1,718	1,404
Other Assets [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	46	54
Level 1 [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	594	486
Level 1 [Member] | Short Term Investments [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	'
Level 1 [Member] | Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	'
Level 1 [Member] | Fixed Maturities [Member] | U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	'
Level 1 [Member] | Fixed Maturities [Member] | Corporate Bonds [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	'
Level 1 [Member] | Fixed Maturities [Member] | Foreign Government and Government Agency Obligations [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	'
Level 1 [Member] | Fixed Maturities [Member] | Mortgage Backed Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	'
Level 1 [Member] | Equity Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	573	457
Level 1 [Member] | Other Assets [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	21	29
Level 2 [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	2,105	1,801
Level 2 [Member] | Short Term Investments [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	37	33
Level 2 [Member] | Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	909	812
Level 2 [Member] | Fixed Maturities [Member] | U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	224	238
Level 2 [Member] | Fixed Maturities [Member] | Corporate Bonds [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	370	321
Level 2 [Member] | Fixed Maturities [Member] | Foreign Government and Government Agency Obligations [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	104	79
Level 2 [Member] | Fixed Maturities [Member] | Mortgage Backed Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	211	174
Level 2 [Member] | Equity Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	1,145	947
Level 2 [Member] | Other Assets [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	14	9
Level 3 [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	18	18
Level 3 [Member] | Short Term Investments [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	'
Level 3 [Member] | Fixed Maturities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	7	2
Level 3 [Member] | Fixed Maturities [Member] | U.S. Government and Government Agency and Authority Obligations [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	1
Level 3 [Member] | Fixed Maturities [Member] | Corporate Bonds [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	1	'
Level 3 [Member] | Fixed Maturities [Member] | Foreign Government and Government Agency Obligations [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	1
Level 3 [Member] | Fixed Maturities [Member] | Mortgage Backed Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	6	'
Level 3 [Member] | Equity Securities [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	'	'
Level 3 [Member] | Other Assets [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Plan assets at fair value	$11	$16

Earnings_Per_Share_Computation

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Basic earnings per share:	'	'	'	'	'	'	'	'	'	'	'
Net Income	$569	$541	$579	$656	$102	$533	$404	$506	$2,345	$1,545	$1,678
Weighted average shares outstanding	'	'	'	'	'	'	'	'	258.2	269.5	289.3
Basic earnings per share	$2.25	$2.11	$2.22	$2.49	$0.39	$1.99	$1.49	$1.85	$9.08	$5.73	$5.80
Diluted earnings per share:	'	'	'	'	'	'	'	'	'	'	'
Net Income	$569	$541	$579	$656	$102	$533	$404	$506	$2,345	$1,545	$1,678
Weighted average shares outstanding	'	'	'	'	'	'	'	'	258.2	269.5	289.3
Additional shares from assumed issuance of shares under stock-based compensation awards	'	'	'	'	'	'	'	'	1.2	1.9	2.1
Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share	'	'	'	'	'	'	'	'	259.4	271.4	291.4
Diluted earnings per share	$2.24	$2.10	$2.21	$2.48	$0.38	$1.98	$1.48	$1.83	$9.04	$5.69	$5.76

Shareholders_Equity_Common_Sto

Shareholders' Equity - Common Stock Activity (Detail)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
				Common Stock [Member]	Common Stock [Member]	Common Stock [Member]	Common Stock [Member]	Treasury Stock, at Cost [Member]	Treasury Stock, at Cost [Member]	Treasury Stock, at Cost [Member]
Balance, beginning of year	'	'	'	371,980,460	371,980,460	371,980,460	371,980,460	110,217,445	99,519,509	74,707,547
Repurchase of shares	'	'	'	'	'	'	'	14,887,701	13,094,640	27,582,889
Share activity under stock-based employee compensation plans	'	'	'	'	'	'	'	-1,431,177	-2,396,704	-2,770,927
Balance, end of year	'	'	'	371,980,460	371,980,460	371,980,460	371,980,460	123,673,969	110,217,445	99,519,509
Common stock outstanding, end of year	248,306,491	261,763,015	272,460,951	'	'	'	'	'	'	'

Shareholders_Equity_Additional

Shareholders' Equity - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
		Federal Insurance Company [Member]	P&C Group [Member]	P&C Group [Member]
Class of Stock [Line Items]	'	'	'	'
Remaining under the share repurchase authorization	$107,000,000	'	'	'
Authorized repurchase of the Corporation's common stock	1,500,000,000	'	'	'
Aggregate statutory capital and surplus	'	14,700,000,000	15,024,000,000	14,117,000,000
Risk-based capital requirement	'	4,900,000,000	'	'
Dividends paid by domestic property and casualty insurance subsidiaries to parent	1,600,000,000	'	'	'
Maximum dividend distribution that may be made by the property and casualty insurance subsidiaries to parent company during 2014 without prior regulatory approval	$2,000,000,000	'	'	'

Shareholders_Equity_Comparison

Shareholders' Equity - Comparison of Shareholders' Equity on GAAP Basis and Policyholders' Surplus on Statutory Basis (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified
Comparison of shareholders' equity on a GAAP basis and policyholders' surplus on a statutory basis	'	'	'
Shareholders' equity	$16,097	$15,827	$15,301
P&C Group [Member]	'	'	'
Comparison of shareholders' equity on a GAAP basis and policyholders' surplus on a statutory basis	'	'	'
Shareholders' equity	17,398	16,833	'
Policyholders' surplus	15,024	14,117	'
Corporate and Other [Member]	'	'	'
Comparison of shareholders' equity on a GAAP basis and policyholders' surplus on a statutory basis	'	'	'
Shareholders' equity	($1,301)	($1,006)	'

Shareholders_Equity_Comparison1

Shareholders' Equity - Comparison of GAAP and Statutory Net Income (Loss) (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Comparison of GAAP and statutory net income (loss)	'	'	'	'	'	'	'	'	'	'	'
GAAP net income (loss)	$569	$541	$579	$656	$102	$533	$404	$506	$2,345	$1,545	$1,678
P&C Group [Member]	'	'	'	'	'	'	'	'	'	'	'
Comparison of GAAP and statutory net income (loss)	'	'	'	'	'	'	'	'	'	'	'
GAAP net income (loss)	'	'	'	'	'	'	'	'	2,480	1,791	1,915
Statutory net income	'	'	'	'	'	'	'	'	2,485	1,936	1,824
Corporate and Other [Member]	'	'	'	'	'	'	'	'	'	'	'
Comparison of GAAP and statutory net income (loss)	'	'	'	'	'	'	'	'	'	'	'
GAAP net income (loss)	'	'	'	'	'	'	'	'	($135)	($246)	($237)

Quarterly_Financial_Data_Summa

Quarterly Financial Data - Summary of Quarterly Financial Data (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Revenues	$3,476	$3,403	$3,551	$3,517	$3,400	$3,362	$3,423	$3,410	$13,947	$13,595	$13,585
Losses and expenses	2,690	2,664	2,755	2,601	3,337	2,635	2,896	2,731	'	'	'
Federal and foreign income tax (credit)	217	198	217	260	-39	194	123	173	892	451	521
NET INCOME	$569	$541	$579	$656	$102	$533	$404	$506	$2,345	$1,545	$1,678
Basic earnings per share	$2.25	$2.11	$2.22	$2.49	$0.39	$1.99	$1.49	$1.85	$9.08	$5.73	$5.80
Diluted earnings per share	$2.24	$2.10	$2.21	$2.48	$0.38	$1.98	$1.48	$1.83	$9.04	$5.69	$5.76
Underwriting ratios	'	'	'	'	'	'	'	'	'	'	'
Losses to premiums earned	0.547	0.53	0.567	0.523	0.803	0.538	0.625	0.58	'	'	'
Expenses to premiums written	0.308	0.327	0.321	0.323	0.309	0.325	0.313	0.322	'	'	'
Combined loss and expense ratio	0.855	0.857	0.888	0.846	1.112	0.863	0.938	0.902	'	'	'

Quarterly_Financial_Data_Summa1

Quarterly Financial Data - Summary of Quarterly Financial Data (Parenthetical) (Detail) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]	'
Net reinsurance reinstatement premium costs	($53)
Net losses related to Storm Sandy	-829
Reduction in net income related to Storm Sandy	($573)
Diluted earnings per share reduction due to Storm Sandy	$2.15
Basic earnings per share reduction due to Storm Sandy	$2.16
Losses to premiums earned, Excluding impact of Storm Sandy	50.90%
Expenses to premiums written, Excluding impact of Storm Sandy	30.40%
Combined loss and expense ratio, Excluding impact of Storm Sandy	81.30%

Consolidated_Summary_of_Invest1

Consolidated Summary of Investments - Other Than Investments in Related Parties (Detail) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	$40,728
Fair Value	42,613
Amount at Which Shown in the Balance Sheet	42,613
Foreign Government and Government Agency Obligations [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	6,719
Fair Value	6,890
Amount at Which Shown in the Balance Sheet	6,890
Residential Mortgage-backed Securities [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	277
Fair Value	299
Amount at Which Shown in the Balance Sheet	299
Commercial Mortgage-backed Securities [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	1,339
Fair Value	1,365
Amount at Which Shown in the Balance Sheet	1,365
Short Term Investments [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	2,114
Fair Value	2,114
Amount at Which Shown in the Balance Sheet	2,114
Fixed Maturities [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	35,959
Fair Value	37,091
Amount at Which Shown in the Balance Sheet	37,091
United States Government and Government Agencies and Authorities [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	401
Fair Value	414
Amount at Which Shown in the Balance Sheet	414
States, Municipalities and Political Subdivisions [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	18,191
Fair Value	18,809
Amount at Which Shown in the Balance Sheet	18,809
Public Utilities, Bonds [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	1,186
Fair Value	1,273
Amount at Which Shown in the Balance Sheet	1,273
All Other Corporate Bonds [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	7,846
Fair Value	8,041
Amount at Which Shown in the Balance Sheet	8,041
Public Utilities, Equities [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	114
Fair Value	170
Amount at Which Shown in the Balance Sheet	170
Banks, Trust and Insurance, Equities [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	88
Fair Value	156
Amount at Which Shown in the Balance Sheet	156
Industrial, Miscellaneous and Other [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	846
Fair Value	1,468
Amount at Which Shown in the Balance Sheet	1,468
Common Stocks [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	1,048
Fair Value	1,794
Amount at Which Shown in the Balance Sheet	1,794
Non-Redeemable Preferred Stocks [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	9
Fair Value	16
Amount at Which Shown in the Balance Sheet	16
Equity Securities [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	1,057
Fair Value	1,810
Amount at Which Shown in the Balance Sheet	1,810
Other Invested Assets [Member]	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'
Cost or Amortized Cost	1,598
Fair Value	1,598
Amount at Which Shown in the Balance Sheet	$1,598

Condensed_Financial_Informatio1

Condensed Financial Information of Parent Company - Balance Sheets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified
Assets	'	'	'
Short Term Investments	$2,114	$2,528	'
Taxable Fixed Maturities (cost $1,095 and $1,273)	37,091	38,076	'
Equity Securities (cost $ - and $176)	1,810	1,663	'
Other Invested Assets	1,598	1,954	'
TOTAL INVESTED ASSETS	42,613	44,221	'
Other Assets	1,205	1,353	'
TOTAL ASSETS	50,433	52,184	50,445
Liabilities	'	'	'
Long Term Debt	3,300	3,575	'
Dividend Payable to Shareholders	110	108	'
Accrued Expenses and Other Liabilities	1,357	2,188	'
TOTAL LIABILITIES	34,336	36,357	'
Shareholders' Equity	'	'	'
Preferred Stock - Authorized 8,000,000 Shares; $1 Par Value; Issued - None	'	'	'
Common Stock - Authorized 1,200,000,000 Shares; $1 Par Value; Issued 371,980,460 Shares	372	372	'
Paid-In Surplus	171	178	'
Retained Earnings	21,902	20,009	'
Accumulated Other Comprehensive Income	1,035	1,431	'
Treasury Stock, at Cost - 123,673,969 and 110,217,445 Shares	-7,383	-6,163	'
TOTAL SHAREHOLDERS' EQUITY	16,097	15,827	15,301
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	50,433	52,184	'
Parent Company [Member]	'	'	'
Assets	'	'	'
Short Term Investments	856	941	'
Taxable Fixed Maturities (cost $1,095 and $1,273)	1,110	1,309	'
Equity Securities (cost $ - and $176)	2	215	'
Other Invested Assets	'	46	'
TOTAL INVESTED ASSETS	1,968	2,511	'
Investment in Consolidated Subsidiaries	17,455	16,900	'
Other Assets	165	190	'
TOTAL ASSETS	19,588	19,601	'
Liabilities	'	'	'
Long Term Debt	3,300	3,575	'
Dividend Payable to Shareholders	110	108	'
Accrued Expenses and Other Liabilities	81	91	'
TOTAL LIABILITIES	3,491	3,774	'
Shareholders' Equity	'	'	'
Preferred Stock - Authorized 8,000,000 Shares; $1 Par Value; Issued - None	'	'	'
Common Stock - Authorized 1,200,000,000 Shares; $1 Par Value; Issued 371,980,460 Shares	372	372	'
Paid-In Surplus	171	178	'
Retained Earnings	21,902	20,009	'
Accumulated Other Comprehensive Income	1,035	1,431	'
Treasury Stock, at Cost - 123,673,969 and 110,217,445 Shares	-7,383	-6,163	'
TOTAL SHAREHOLDERS' EQUITY	16,097	15,827	'
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$19,588	$19,601	'

Condensed_Financial_Informatio2

Condensed Financial Information of Parent Company - Balance Sheets (Parenthetical) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, except Share data, unless otherwise specified
Fixed Maturities, cost	$35,959	$35,398
Equity Securities, cost	1,057	1,244
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Preferred Stock, Par Value	$1	$1
Preferred Stock, Shares Issued	'	'
Common Stock, Shares Authorized	1,200,000,000	1,200,000,000
Common Stock, Par Value	$1	$1
Common Stock, Shares Issued	371,980,460	371,980,460
Treasury Stock, Shares	123,673,969	110,217,445
Parent Company [Member]	'	'
Fixed Maturities, cost	1,095	1,273
Equity Securities, cost	'	$176
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Preferred Stock, Par Value	$1	$1
Preferred Stock, Shares Issued	0	0
Common Stock, Shares Authorized	1,200,000,000	1,200,000,000
Common Stock, Par Value	$1	$1
Common Stock, Shares Issued	371,980,460	371,980,460
Treasury Stock, Shares	123,673,969	110,217,445

Condensed_Financial_Informatio3

Condensed Financial Information of Parent Company - Statements of Income (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues	'	'	'	'	'	'	'	'	'	'	'
Investment Income	'	'	'	'	'	'	'	'	$1,465	$1,556	$1,644
Other Revenues	'	'	'	'	'	'	'	'	14	8	9
Realized Investment Gains (Losses), Net	'	'	'	'	'	'	'	'	402	193	288
TOTAL REVENUES	3,476	3,403	3,551	3,517	3,400	3,362	3,423	3,410	13,947	13,595	13,585
Expenses	'	'	'	'	'	'	'	'	'	'	'
Corporate Expenses	'	'	'	'	'	'	'	'	254	270	287
Investment Expenses	'	'	'	'	'	'	'	'	49	38	39
Other Expenses	'	'	'	'	'	'	'	'	22	11	11
Federal and Foreign Income Tax	217	198	217	260	-39	194	123	173	892	451	521
NET INCOME	569	541	579	656	102	533	404	506	2,345	1,545	1,678
Other Comprehensive Income (Loss), Net of Tax	'	'	'	'	'	'	'	'	-396	236	405
COMPREHENSIVE INCOME	'	'	'	'	'	'	'	'	1,949	1,781	2,083
Parent Company [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	'	'	'	'	'
Investment Income	'	'	'	'	'	'	'	'	29	38	46
Other Revenues	'	'	'	'	'	'	'	'	6	'	'
Realized Investment Gains (Losses), Net	'	'	'	'	'	'	'	'	99	-6	9
TOTAL REVENUES	'	'	'	'	'	'	'	'	134	32	55
Expenses	'	'	'	'	'	'	'	'	'	'	'
Corporate Expenses	'	'	'	'	'	'	'	'	262	268	285
Investment Expenses	'	'	'	'	'	'	'	'	4	2	3
Other Expenses	'	'	'	'	'	'	'	'	8	'	'
TOTAL EXPENSES	'	'	'	'	'	'	'	'	274	270	288
Loss before Federal and Foreign Income Tax and Equity in Net Income of Consolidated Subsidiaries	'	'	'	'	'	'	'	'	-140	-238	-233
Federal and Foreign Income Tax	'	'	'	'	'	'	'	'	'	4	1
Loss before Equity in Net Income of Consolidated Subsidiaries	'	'	'	'	'	'	'	'	-140	-242	-234
Equity in Net Income of Consolidated Subsidiaries	'	'	'	'	'	'	'	'	2,485	1,787	1,912
NET INCOME	'	'	'	'	'	'	'	'	2,345	1,545	1,678
Other Comprehensive Income (Loss), Net of Tax	'	'	'	'	'	'	'	'	-396	236	405
COMPREHENSIVE INCOME	'	'	'	'	'	'	'	'	$1,949	$1,781	$2,083

Condensed_Financial_Informatio4

Condensed Financial Information of Parent Company - Statements Of Cash Flows (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities	'	'	'
Net Income	$2,345	$1,545	$1,678
Adjustments to Reconcile Net Income to Net Cash Used in Operating Activities	'	'	'
Realized Investment Losses (Gains), Net	-402	-193	-288
Other, Net	-20	84	-27
NET CASH PROVIDED BY OPERATING ACTIVITIES	1,731	2,299	1,878
Cash Flows from Investing Activities	'	'	'
Proceeds from Fixed Maturities Sales	2,449	2,271	1,730
Maturities, Calls and Redemptions	4,909	4,290	3,540
Proceeds from Sales of Equity Securities	545	160	167
Purchases of Fixed Maturities	-8,275	-7,247	-5,014
Investments in Other Invested Assets, Net	498	293	285
Decrease (Increase) in Short Term Investments, Net	383	-629	11
Other, Net	-6	'	'
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	252	-972	580
Cash Flows from Financing Activities	'	'	'
Repayment of Long Term Debt	-275	'	-400
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	38	74	80
Repurchase of Shares	-1,288	-959	-1,707
Dividends Paid to Shareholders	-450	-438	-450
NET CASH USED IN FINANCING ACTIVITIES	-1,981	-1,335	-2,470
Net Increase in Cash	2	-8	-12
Cash at Beginning of Year	50	58	70
CASH AT END OF YEAR	52	50	58
Parent Company [Member]	'	'	'
Cash Flows from Operating Activities	'	'	'
Net Income	2,345	1,545	1,678
Adjustments to Reconcile Net Income to Net Cash Used in Operating Activities	'	'	'
Equity in Net Income of Consolidated Subsidiaries	-2,485	-1,787	-1,912
Realized Investment Losses (Gains), Net	-99	6	-9
Other, Net	21	57	-28
NET CASH PROVIDED BY OPERATING ACTIVITIES	-218	-179	-271
Cash Flows from Investing Activities	'	'	'
Proceeds from Fixed Maturities Sales	227	24	2
Maturities, Calls and Redemptions	150	673	456
Proceeds from Sales of Equity Securities	296	'	9
Purchases of Fixed Maturities	-198	-1,046	-257
Investments in Other Invested Assets, Net	22	'	'
Decrease (Increase) in Short Term Investments, Net	85	89	-219
Dividends Received from Consolidated Insurance Subsidiaries	1,564	1,760	2,700
Distributions Received from Consolidated Non-Insurance Subsidiaries	1	1	1
Other, Net	46	1	56
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	2,193	1,502	2,748
Cash Flows from Financing Activities	'	'	'
Repayment of Long Term Debt	-275	'	-400
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	38	74	80
Repurchase of Shares	-1,288	-959	-1,707
Dividends Paid to Shareholders	-450	-438	-450
NET CASH USED IN FINANCING ACTIVITIES	-1,975	-1,323	-2,477
Net Increase in Cash	'	'	'
Cash at Beginning of Year	'	'	'
CASH AT END OF YEAR	'	'	'

Condensed_Financial_Informatio5

Condensed Financial Information of Parent Company - Statements Of Cash Flows (Parenthetical) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
In Millions, unless otherwise specified					Alterra Common Stock [Member]	Alterra Warrants [Member]	Markel Corporation [Member]
Condensed Financial Statements, Captions [Line Items]	'	'	'	'	'	'	'
Holdings of common stock and warrants, cost basis	'	'	'	'	$177	$63	'
Transferred, common stock value	'	'	'	'	'	'	226
Cash	$52	$50	$58	$70	'	'	$98

Consolidated_Supplementary_Ins1

Consolidated Supplementary Insurance Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'
Deferred Policy Acquisition Costs	$1,255	$1,206	$1,210
Unpaid Losses	23,146	23,963	23,068
Unearned Premiums	6,423	6,361	6,322
Premiums Earned	12,066	11,838	11,644
Net Investment Income	1,391	1,482	1,562
Insurance Losses	6,520	7,507	7,407
Amortization of Deferred Policy Acquisition Costs	2,454	2,411	2,330
Other Insurance Operating Costs and Expenses	1,417	1,372	1,333
Premiums Written	12,224	11,870	11,758
Personal insurance [Member]	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'
Deferred Policy Acquisition Costs	505	477	466
Unpaid Losses	2,235	2,493	2,241
Unearned Premiums	2,216	2,133	2,048
Premiums Earned	4,214	4,024	3,917
Net Investment Income	'	'	'
Insurance Losses	2,224	2,417	2,508
Amortization of Deferred Policy Acquisition Costs	982	942	900
Other Insurance Operating Costs and Expenses	465	458	436
Premiums Written	4,322	4,125	3,977
Commercial insurance [Member]	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'
Deferred Policy Acquisition Costs	493	477	475
Unpaid Losses	13,147	13,288	12,422
Unearned Premiums	2,792	2,794	2,746
Premiums Earned	5,237	5,144	4,945
Net Investment Income	'	'	'
Insurance Losses	2,891	3,512	3,366
Amortization of Deferred Policy Acquisition Costs	970	970	929
Other Insurance Operating Costs and Expenses	665	620	617
Premiums Written	5,273	5,174	5,051
Specialty insurance [Member]	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'
Deferred Policy Acquisition Costs	257	252	269
Unpaid Losses	7,307	7,622	7,677
Unearned Premiums	1,412	1,429	1,519
Premiums Earned	2,618	2,666	2,769
Net Investment Income	'	'	'
Insurance Losses	1,417	1,622	1,558
Amortization of Deferred Policy Acquisition Costs	502	499	501
Other Insurance Operating Costs and Expenses	287	293	278
Premiums Written	2,633	2,568	2,720
Reinsurance Assumed [Member]	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'
Deferred Policy Acquisition Costs	'	'	'
Unpaid Losses	457	560	728
Unearned Premiums	3	5	9
Premiums Earned	-3	4	13
Net Investment Income	'	'	'
Insurance Losses	-12	-44	-25
Amortization of Deferred Policy Acquisition Costs	'	'	'
Other Insurance Operating Costs and Expenses	'	1	2
Premiums Written	-4	3	10
Investments [Member]	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'
Deferred Policy Acquisition Costs	'	'	'
Unpaid Losses	'	'	'
Unearned Premiums	'	'	'
Premiums Earned	'	'	'
Net Investment Income	1,391	1,482	1,562
Insurance Losses	'	'	'
Amortization of Deferred Policy Acquisition Costs	'	'	'
Other Insurance Operating Costs and Expenses	'	'	'
Premiums Written	'	'	'